diff --git a/Bugsnag.xcodeproj/project.pbxproj b/Bugsnag.xcodeproj/project.pbxproj
index 28984bfe3..082d79853 100644
--- a/Bugsnag.xcodeproj/project.pbxproj
+++ b/Bugsnag.xcodeproj/project.pbxproj
@@ -723,6 +723,10 @@
 		01E8765E256684E700F4B70A /* URLSessionMock.m in Sources */ = {isa = PBXBuildFile; fileRef = 01E8765D256684E700F4B70A /* URLSessionMock.m */; };
 		01E8765F256684E700F4B70A /* URLSessionMock.m in Sources */ = {isa = PBXBuildFile; fileRef = 01E8765D256684E700F4B70A /* URLSessionMock.m */; };
 		01E87660256684E700F4B70A /* URLSessionMock.m in Sources */ = {isa = PBXBuildFile; fileRef = 01E8765D256684E700F4B70A /* URLSessionMock.m */; };
+		01F9FCB628929336005EDD8C /* BSGSerializationTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 01F9FCB528929336005EDD8C /* BSGSerializationTests.m */; };
+		01F9FCB728929336005EDD8C /* BSGSerializationTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 01F9FCB528929336005EDD8C /* BSGSerializationTests.m */; };
+		01F9FCB828929336005EDD8C /* BSGSerializationTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 01F9FCB528929336005EDD8C /* BSGSerializationTests.m */; };
+		01F9FCB928929336005EDD8C /* BSGSerializationTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 01F9FCB528929336005EDD8C /* BSGSerializationTests.m */; };
 		3A700A9424A63ABC0068CD1B /* BugsnagThread.h in Headers */ = {isa = PBXBuildFile; fileRef = 3A700A8024A63A8E0068CD1B /* BugsnagThread.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		3A700A9524A63AC50068CD1B /* BugsnagSession.h in Headers */ = {isa = PBXBuildFile; fileRef = 3A700A8124A63A8E0068CD1B /* BugsnagSession.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		3A700A9624A63AC60068CD1B /* BugsnagStackframe.h in Headers */ = {isa = PBXBuildFile; fileRef = 3A700A8224A63A8E0068CD1B /* BugsnagStackframe.h */; settings = {ATTRIBUTES = (Public, ); }; };
@@ -1628,6 +1632,7 @@
 		01DE903B26CEAF9E00455213 /* BSGUtilsTests.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = BSGUtilsTests.m; sourceTree = "<group>"; };
 		01E8765C256684E700F4B70A /* URLSessionMock.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = URLSessionMock.h; sourceTree = "<group>"; };
 		01E8765D256684E700F4B70A /* URLSessionMock.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = URLSessionMock.m; sourceTree = "<group>"; };
+		01F9FCB528929336005EDD8C /* BSGSerializationTests.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = BSGSerializationTests.m; sourceTree = "<group>"; };
 		3A700A8024A63A8E0068CD1B /* BugsnagThread.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = BugsnagThread.h; sourceTree = "<group>"; };
 		3A700A8124A63A8E0068CD1B /* BugsnagSession.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = BugsnagSession.h; sourceTree = "<group>"; };
 		3A700A8224A63A8E0068CD1B /* BugsnagStackframe.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = BugsnagStackframe.h; sourceTree = "<group>"; };
@@ -2033,6 +2038,7 @@
 				0163BF5825823D8D008DC28B /* BSGNotificationBreadcrumbsTests.m */,
 				008966C82486D43600DC48C2 /* BSGOutOfMemoryTests.m */,
 				0130DEF82880203A00E5953F /* BSGRunContextTests.m */,
+				01F9FCB528929336005EDD8C /* BSGSerializationTests.m */,
 				CB6419AA25A73E8C00613D25 /* BSGStorageMigratorTests.m */,
 				017DCF9A287422BB000ECB22 /* BSGTelemetryTests.m */,
 				01DE903B26CEAF9E00455213 /* BSGUtilsTests.m */,
@@ -3236,6 +3242,7 @@
 				CBA2249B251E429C00B87416 /* TestSupport.m in Sources */,
 				008967332486D43700DC48C2 /* BugsnagClientTests.m in Sources */,
 				004E353F2487B3BD007FBAE4 /* BugsnagSwiftConfigurationTests.swift in Sources */,
+				01F9FCB628929336005EDD8C /* BSGSerializationTests.m in Sources */,
 				008967542486D43700DC48C2 /* BugsnagOnCrashTest.m in Sources */,
 				008967152486D43700DC48C2 /* BugsnagCollectionsTests.m in Sources */,
 				01E8765E256684E700F4B70A /* URLSessionMock.m in Sources */,
@@ -3395,6 +3402,7 @@
 				0089671C2486D43700DC48C2 /* BugsnagSessionTest.m in Sources */,
 				008967AC2486D43700DC48C2 /* BSG_KSMachTests.m in Sources */,
 				0163BF5A25823D8D008DC28B /* BSGNotificationBreadcrumbsTests.m in Sources */,
+				01F9FCB728929336005EDD8C /* BSGSerializationTests.m in Sources */,
 				01BDB1FD25DEBFB300A91FAF /* BSGEventUploadKSCrashReportOperationTests.m in Sources */,
 				00896A452486DBF000DC48C2 /* BugsnagConfigurationTests.m in Sources */,
 				008967492486D43700DC48C2 /* BugsnagUserTest.m in Sources */,
@@ -3543,6 +3551,7 @@
 				E701FAAD2490EFD9008D842F /* EventApiValidationTest.m in Sources */,
 				008967472486D43700DC48C2 /* BugsnagTests.m in Sources */,
 				010993A6273D188B00128BBE /* BSGFeatureFlagStoreTests.m in Sources */,
+				01F9FCB828929336005EDD8C /* BSGSerializationTests.m in Sources */,
 				008967A72486D43700DC48C2 /* KSString_Tests.m in Sources */,
 				0089671A2486D43700DC48C2 /* BugsnagErrorTest.m in Sources */,
 				008967172486D43700DC48C2 /* BugsnagCollectionsTests.m in Sources */,
@@ -3843,6 +3852,7 @@
 				CB28F0A228294D4F003AB200 /* KSCrashReportWriterTests.m in Sources */,
 				CB28F0D3282A4B91003AB200 /* BugsnagErrorTest.m in Sources */,
 				CB28F0DE282A4BEE003AB200 /* BugsnagSessionTrackerStopTest.m in Sources */,
+				01F9FCB928929336005EDD8C /* BSGSerializationTests.m in Sources */,
 				CB28F0B328294DD0003AB200 /* BSGClientObserverTests.m in Sources */,
 				CB28F0B128294D4F003AB200 /* KSCrashSentry_Tests.m in Sources */,
 				CB28F0B228294D52003AB200 /* XCTestCase+KSCrash.m in Sources */,
diff --git a/Bugsnag/Breadcrumbs/BugsnagBreadcrumbs.h b/Bugsnag/Breadcrumbs/BugsnagBreadcrumbs.h
index 1657d4b64..3a0e8fdde 100644
--- a/Bugsnag/Breadcrumbs/BugsnagBreadcrumbs.h
+++ b/Bugsnag/Breadcrumbs/BugsnagBreadcrumbs.h
@@ -23,7 +23,7 @@ NS_ASSUME_NONNULL_BEGIN
 - (instancetype)initWithConfiguration:(BugsnagConfiguration *)config;
 
 /**
- * The breadcrumbs stored in memory.
+ * Returns an array of new objects representing the breadcrumbs stored in memory.
  */
 @property (readonly, nonatomic) NSArray<BugsnagBreadcrumb *> *breadcrumbs;
 
diff --git a/Bugsnag/Configuration/BugsnagConfiguration.m b/Bugsnag/Configuration/BugsnagConfiguration.m
index 5f4c93b8c..a69d3e8a2 100644
--- a/Bugsnag/Configuration/BugsnagConfiguration.m
+++ b/Bugsnag/Configuration/BugsnagConfiguration.m
@@ -94,6 +94,7 @@ - (nonnull id)copyWithZone:(nullable NSZone *)zone {
     [copy setSendLaunchCrashesSynchronously:self.sendLaunchCrashesSynchronously];
     [copy setMaxPersistedEvents:self.maxPersistedEvents];
     [copy setMaxPersistedSessions:self.maxPersistedSessions];
+    [copy setMaxStringValueLength:self.maxStringValueLength];
     [copy setMaxBreadcrumbs:self.maxBreadcrumbs];
     [copy setNotifier:self.notifier];
     [copy setFeatureFlagStore:self.featureFlagStore];
@@ -189,6 +190,7 @@ - (instancetype)initWithApiKey:(NSString *)apiKey {
     _maxBreadcrumbs = 50;
     _maxPersistedEvents = 32;
     _maxPersistedSessions = 128;
+    _maxStringValueLength = 10000;
     _autoTrackSessions = YES;
 #if BSG_HAVE_MACH_THREADS
     _sendThreads = BSGThreadSendPolicyAlways;
diff --git a/Bugsnag/Delivery/BSGEventUploadOperation.m b/Bugsnag/Delivery/BSGEventUploadOperation.m
index 33b047ca4..3c9e4b002 100644
--- a/Bugsnag/Delivery/BSGEventUploadOperation.m
+++ b/Bugsnag/Delivery/BSGEventUploadOperation.m
@@ -95,9 +95,13 @@ - (void)runWithDelegate:(id<BSGEventUploadOperationDelegate>)delegate completion
     
     NSDictionary *eventPayload;
     @try {
+        [event truncateStrings:configuration.maxStringValueLength];
         eventPayload = [event toJsonWithRedactedKeys:configuration.redactedKeys];
     } @catch (NSException *exception) {
         bsg_log_err(@"Discarding event %@ because an exception was thrown by -toJsonWithRedactedKeys: %@", self.name, exception);
+        [BSGInternalErrorReporter.sharedInstance reportException:exception diagnostics:nil groupingHash:
+         [NSString stringWithFormat:@"BSGEventUploadOperation -[runWithDelegate:completionHandler:] %@ %@",
+          exception.name, exception.reason]];
         [self deleteEvent];
         completionHandler();
         return;
diff --git a/Bugsnag/Helpers/BSGSerialization.h b/Bugsnag/Helpers/BSGSerialization.h
index 70047c173..0f3c85d0f 100644
--- a/Bugsnag/Helpers/BSGSerialization.h
+++ b/Bugsnag/Helpers/BSGSerialization.h
@@ -1,40 +1,32 @@
-#ifndef BugsnagJSONSerializable_h
-#define BugsnagJSONSerializable_h
-
 #import <Foundation/Foundation.h>
 
-/**
- Removes any values which would be rejected by NSJSONSerialization for
- documented reasons
-
- @param input an array
- @return a new array
- */
-NSArray *_Nonnull BSGSanitizeArray(NSArray *_Nonnull input);
+NS_ASSUME_NONNULL_BEGIN
 
 /**
  Removes any values which would be rejected by NSJSONSerialization for
- documented reasons
+ documented reasons or is NSNull
 
  @param input a dictionary
  @return a new dictionary
  */
-NSDictionary *_Nonnull BSGSanitizeDict(NSDictionary *_Nonnull input);
-
-/**
- Checks whether the base type would be accepted by the serialization process
-
- @param obj any object or nil
- @return YES if the object is an Array, Dictionary, String, Number, or NSNull
- */
-BOOL BSGIsSanitizedType(id _Nullable obj);
+NSMutableDictionary * BSGSanitizeDict(NSDictionary *input);
 
 /**
  Cleans the object, including nested dictionary and array values
 
  @param obj any object or nil
- @return a new object for serialization or nil if the obj was incompatible
+ @return a new object for serialization or nil if the obj was incompatible or NSNull
  */
 id _Nullable BSGSanitizeObject(id _Nullable obj);
 
-#endif
+typedef struct _BSGTruncateContext {
+    NSUInteger maxLength;
+    NSUInteger strings;
+    NSUInteger length;
+} BSGTruncateContext;
+
+NSString * BSGTruncateString(BSGTruncateContext *context, NSString *string);
+
+id BSGTruncateStrings(BSGTruncateContext *context, id object);
+
+NS_ASSUME_NONNULL_END
diff --git a/Bugsnag/Helpers/BSGSerialization.m b/Bugsnag/Helpers/BSGSerialization.m
index 64751c377..135611ef1 100644
--- a/Bugsnag/Helpers/BSGSerialization.m
+++ b/Bugsnag/Helpers/BSGSerialization.m
@@ -1,41 +1,26 @@
 #import "BSGSerialization.h"
-#import "BugsnagLogger.h"
+
 #import "BSGJSONSerialization.h"
+#import "BugsnagLogger.h"
 
-BOOL BSGIsSanitizedType(id obj) {
-    static dispatch_once_t onceToken;
-    static NSArray *allowedTypes = nil;
-    dispatch_once(&onceToken, ^{
-      allowedTypes = @[
-          [NSArray class], [NSDictionary class], [NSNull class],
-          [NSNumber class], [NSString class]
-      ];
-    });
-
-    for (Class klass in allowedTypes) {
-        if ([obj isKindOfClass:klass])
-            return YES;
-    }
-    return NO;
-}
+static NSArray * BSGSanitizeArray(NSArray *input);
 
 id BSGSanitizeObject(id obj) {
-    if ([obj isKindOfClass:[NSNumber class]]) {
-        NSNumber *number = obj;
-        if (![number isEqualToNumber:[NSDecimalNumber notANumber]] &&
-            !isinf([number doubleValue]))
-            return obj;
-    } else if ([obj isKindOfClass:[NSArray class]]) {
+    if ([obj isKindOfClass:[NSArray class]]) {
         return BSGSanitizeArray(obj);
     } else if ([obj isKindOfClass:[NSDictionary class]]) {
         return BSGSanitizeDict(obj);
-    } else if (BSGIsSanitizedType(obj)) {
+    } else if ([obj isKindOfClass:[NSString class]]) {
+        return obj;
+    } else if ([obj isKindOfClass:[NSNumber class]]
+               && ![obj isEqualToNumber:[NSDecimalNumber notANumber]]
+               && !isinf([obj doubleValue])) {
         return obj;
     }
     return nil;
 }
 
-NSDictionary *_Nonnull BSGSanitizeDict(NSDictionary *input) {
+NSMutableDictionary * BSGSanitizeDict(NSDictionary *input) {
     __block NSMutableDictionary *output =
         [NSMutableDictionary dictionaryWithCapacity:[input count]];
     [input enumerateKeysAndObjectsUsingBlock:^(id _Nonnull key, id _Nonnull obj,
@@ -49,7 +34,7 @@ id BSGSanitizeObject(id obj) {
     return output;
 }
 
-NSArray *BSGSanitizeArray(NSArray *input) {
+static NSArray * BSGSanitizeArray(NSArray *input) {
     NSMutableArray *output = [NSMutableArray arrayWithCapacity:[input count]];
     for (id obj in input) {
         id cleanedObject = BSGSanitizeObject(obj);
@@ -58,3 +43,37 @@ id BSGSanitizeObject(id obj) {
     }
     return output;
 }
+
+NSString * BSGTruncateString(BSGTruncateContext *context, NSString *string) {
+    const NSUInteger inputLength = string.length;
+    if (inputLength <= context->maxLength) return string;
+    // Prevent chopping in the middle of a composed character sequence
+    NSRange range = [string rangeOfComposedCharacterSequenceAtIndex:context->maxLength];
+    NSString *output = [string substringToIndex:range.location];
+    NSUInteger count = inputLength - range.location;
+    context->strings++;
+    context->length += count;
+    return [output stringByAppendingFormat:@"\n***%lu CHARS TRUNCATED***", (unsigned long)count];
+}
+
+id BSGTruncateStrings(BSGTruncateContext *context, id object) {
+    if ([object isKindOfClass:[NSString class]]) {
+        return BSGTruncateString(context, object);
+    }
+    if ([object isKindOfClass:[NSDictionary class]]) {
+        NSMutableDictionary *output = [NSMutableDictionary dictionaryWithCapacity:((NSDictionary *)object).count];
+        for (NSString *key in (NSDictionary *)object) {
+            id value = ((NSDictionary *)object)[key];
+            output[key] = BSGTruncateStrings(context, value);
+        }
+        return output;
+    }
+    if ([object isKindOfClass:[NSArray class]]) {
+        NSMutableArray *output = [NSMutableArray arrayWithCapacity:((NSArray *)object).count];
+        for (id element in (NSArray *)object) {
+            [output addObject:BSGTruncateStrings(context, element)];
+        }
+        return output;
+    }
+    return object;
+}
diff --git a/Bugsnag/Metadata/BugsnagMetadata.m b/Bugsnag/Metadata/BugsnagMetadata.m
index 092fc2856..88b56f2a6 100644
--- a/Bugsnag/Metadata/BugsnagMetadata.m
+++ b/Bugsnag/Metadata/BugsnagMetadata.m
@@ -56,7 +56,7 @@ - (instancetype)initWithDictionary:(NSDictionary *)dict {
     if ((self = [super init])) {
         // Ensure that the instantiating dictionary is mutable.
         // Saves checks later.
-        _dictionary = [self sanitizeDictionary:dict];
+        _dictionary = BSGSanitizeDict(dict);
         self.stateEventBlocks = [NSMutableArray new];
     }
     if (self.observer) {
@@ -65,44 +65,6 @@ - (instancetype)initWithDictionary:(NSDictionary *)dict {
     return self;
 }
 
-/**
- * Sanitizes the given dictionary to prevent [NSNull null] values from being added
- * to the metadata when deserializing a payload.
- *
- * @param dictionary the input dictionary
- * @return a sanitized dictionary
- */
-- (NSMutableDictionary *)sanitizeDictionary:(NSDictionary *)dictionary {
-    NSMutableDictionary *input = [dictionary mutableCopy];
-
-    for (NSString *key in [input allKeys]) {
-        id obj = input[key];
-
-        if (obj == [NSNull null]) {
-            [input removeObjectForKey:key];
-        } else if ([obj isKindOfClass:[NSDictionary class]]) {
-            input[key] = [self sanitizeDictionary:obj];
-        } else if ([obj isKindOfClass:[NSArray class]]) {
-            input[key] = [self sanitizeArray:obj];
-        }
-    }
-    return input;
-}
-
-- (NSMutableArray *)sanitizeArray:(NSArray *)obj {
-    NSMutableArray *ary = [obj mutableCopy];
-    [ary removeObject:[NSNull null]];
-
-    for (NSUInteger k = 0; k < [ary count]; ++k) {
-        if ([ary[k] isKindOfClass:[NSDictionary class]]) {
-            ary[k] = [self sanitizeDictionary:ary[k]];
-        } else if ([ary[k] isKindOfClass:[NSArray class]]) {
-            ary[k] = [self sanitizeArray:ary[k]];
-        }
-    }
-    return ary;
-}
-
 - (NSDictionary *)toDictionary {
     @synchronized (self) {
         return [self.dictionary mutableCopy];
diff --git a/Bugsnag/Payload/BugsnagEvent+Private.h b/Bugsnag/Payload/BugsnagEvent+Private.h
index c822eac74..c7f3c0095 100644
--- a/Bugsnag/Payload/BugsnagEvent+Private.h
+++ b/Bugsnag/Payload/BugsnagEvent+Private.h
@@ -43,7 +43,7 @@ NS_ASSUME_NONNULL_BEGIN
 /// An array of string representations of BSGErrorType describing the types of stackframe / stacktrace in this error.
 @property (readonly, nonatomic) NSArray<NSString *> *stacktraceTypes;
 
-/// Usage telemetry info, from BSGTelemetryCreateUsage()
+/// Usage telemetry info, from BSGTelemetryCreateUsage(), or nil if BSGTelemetryUsage is not enabled.
 @property (readwrite, nullable, nonatomic) NSDictionary *usage;
 
 @property (readwrite, nonnull, nonatomic) BugsnagUser *user;
@@ -73,6 +73,8 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (NSDictionary *)toJsonWithRedactedKeys:(nullable NSSet *)redactedKeys;
 
+- (void)truncateStrings:(NSUInteger)maxLength;
+
 - (void)notifyUnhandledOverridden;
 
 @end
diff --git a/Bugsnag/Payload/BugsnagEvent.m b/Bugsnag/Payload/BugsnagEvent.m
index 76b219580..46559fe83 100644
--- a/Bugsnag/Payload/BugsnagEvent.m
+++ b/Bugsnag/Payload/BugsnagEvent.m
@@ -8,6 +8,7 @@
 
 #import "BugsnagEvent+Private.h"
 
+#import "BSGDefines.h"
 #import "BSGFeatureFlagStore.h"
 #import "BSGKeys.h"
 #import "BSGSerialization.h"
@@ -31,7 +32,6 @@
 #import "BugsnagStacktrace.h"
 #import "BugsnagThread+Private.h"
 #import "BugsnagUser+Private.h"
-#import "BSGDefines.h"
 
 static NSString * const RedactedMetadataValue = @"[REDACTED]";
 
@@ -690,6 +690,32 @@ - (void)symbolicateIfNeeded {
     }
 }
 
+- (void)truncateStrings:(NSUInteger)maxLength {
+    BSGTruncateContext context = {
+        .maxLength = maxLength
+    };
+    
+    for (BugsnagBreadcrumb *breadcrumb in self.breadcrumbs) {
+        breadcrumb.message = BSGTruncateString(&context, breadcrumb.message);
+        breadcrumb.metadata = BSGTruncateStrings(&context, breadcrumb.metadata);
+    }
+    
+    BugsnagMetadata *metadata = self.metadata; 
+    if (metadata) {
+        self.metadata = [[BugsnagMetadata alloc] initWithDictionary:
+                         BSGTruncateStrings(&context, metadata.dictionary)];
+    }
+    
+    NSDictionary *usage = self.usage;
+    if (usage) {
+        self.usage = BSGDictMerge(@{
+            @"system": @{
+                @"stringCharsTruncated": @(context.length),
+                @"stringsTruncated": @(context.strings)}
+        }, usage);
+    }
+}
+
 - (BOOL)unhandled {
     return self.handledState.unhandled;
 }
diff --git a/Bugsnag/include/Bugsnag/BugsnagConfiguration.h b/Bugsnag/include/Bugsnag/BugsnagConfiguration.h
index 60b921451..7bdf59201 100644
--- a/Bugsnag/include/Bugsnag/BugsnagConfiguration.h
+++ b/Bugsnag/include/Bugsnag/BugsnagConfiguration.h
@@ -334,6 +334,15 @@ BUGSNAG_EXTERN
  */
 @property (nonatomic) NSUInteger maxBreadcrumbs;
 
+/**
+ * The maximum length of breadcrumb messages and metadata string values.
+ * 
+ * Values longer than this will be truncated prior to sending, after running any OnSendError blocks.
+ *
+ * The default value is 10000.
+ */
+@property (nonatomic) NSUInteger maxStringValueLength;
+
 /**
  * Whether User information should be persisted to disk between application runs.
  * Defaults to True.
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 829ee6a1c..5aaebdade 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,9 @@ Changelog
 
 ### Enhancements
 
+* Truncate breadcrumb and metadata strings that are longer than `configuration.maxStringValueLength`.
+  [#1449](https://github.com/bugsnag/bugsnag-cocoa/pull/1449)
+
 * Add `+[BugsnagStackframe stackframesWithCallStackReturnAddresses:]` to public headers. 
   [#1446](https://github.com/bugsnag/bugsnag-cocoa/pull/1446)
 
diff --git a/Tests/BugsnagTests/BSGSerializationTests.m b/Tests/BugsnagTests/BSGSerializationTests.m
new file mode 100644
index 000000000..c36621781
--- /dev/null
+++ b/Tests/BugsnagTests/BSGSerializationTests.m
@@ -0,0 +1,97 @@
+//
+//  BSGSerializationTests.m
+//  Bugsnag
+//
+//  Created by Nick Dowell on 28/07/2022.
+//  Copyright © 2022 Bugsnag Inc. All rights reserved.
+//
+
+#import <XCTest/XCTest.h>
+
+#import "BSGSerialization.h"
+
+@interface BSGSerializationTests : XCTestCase
+
+@end
+
+@implementation BSGSerializationTests
+
+- (void)testSanitizeObject {
+    XCTAssertEqualObjects(BSGSanitizeObject(@""), @"");
+    XCTAssertEqualObjects(BSGSanitizeObject(@42), @42);
+    XCTAssertEqualObjects(BSGSanitizeObject(@[@42]), @[@42]);
+    XCTAssertEqualObjects(BSGSanitizeObject(@[self]), @[]);
+    XCTAssertEqualObjects(BSGSanitizeObject(@{@"a": @"b"}), @{@"a": @"b"});
+    XCTAssertEqualObjects(BSGSanitizeObject(@{@"self": self}), @{});
+    XCTAssertNil(BSGSanitizeObject(@(INFINITY)));
+    XCTAssertNil(BSGSanitizeObject(@(NAN)));
+    XCTAssertNil(BSGSanitizeObject([NSDate date]));
+    XCTAssertNil(BSGSanitizeObject([NSDecimalNumber notANumber]));
+    XCTAssertNil(BSGSanitizeObject([NSNull null]));
+    XCTAssertNil(BSGSanitizeObject(self));
+}
+
+- (void)testTruncateString {
+    BSGTruncateContext context = {0};
+    
+    context.maxLength = NSUIntegerMax;
+    XCTAssertEqualObjects(BSGTruncateString(&context, @"Hello, world!"), @"Hello, world!");
+    XCTAssertEqual(context.strings, 0);
+    XCTAssertEqual(context.length, 0);
+    
+    context.maxLength = 5;
+    XCTAssertEqualObjects(BSGTruncateString(&context, @"Hello, world!"), @"Hello"
+                          "\n***8 CHARS TRUNCATED***");
+    XCTAssertEqual(context.strings, 1);
+    XCTAssertEqual(context.length, 8);
+    
+    // Verify that emoji (composed character sequences) are not partially truncated
+    // Note when adding tests that older OSes like iOS 9 don't understand more recently
+    // added emoji like 🏴󠁧󠁢󠁥󠁮󠁧󠁿 and 👩🏾‍🚀 and therefore won't be able to avoid slicing them.
+    
+    context.maxLength = 10;
+    XCTAssertEqualObjects(BSGTruncateString(&context, @"Emoji: 👍🏾"), @"Emoji: "
+                          "\n***4 CHARS TRUNCATED***");
+    XCTAssertEqual(context.strings, 2);
+    XCTAssertEqual(context.length, 12);
+}
+
+- (void)testTruncateStringsWithString {
+    BSGTruncateContext context = (BSGTruncateContext){.maxLength = 3};
+    XCTAssertEqualObjects(BSGTruncateStrings(&context, @"foo bar"), @"foo"
+                          "\n***4 CHARS TRUNCATED***");
+    XCTAssertEqual(context.strings, 1);
+    XCTAssertEqual(context.length, 4);
+}
+
+- (void)testTruncateStringsWithArray {
+    BSGTruncateContext context = (BSGTruncateContext){.maxLength = 3};
+    XCTAssertEqualObjects(BSGTruncateStrings(&context, @[@"foo bar"]),
+                          @[@"foo"
+                            "\n***4 CHARS TRUNCATED***"]);
+    XCTAssertEqual(context.strings, 1);
+    XCTAssertEqual(context.length, 4);
+}
+
+- (void)testTruncateStringsWithObject {
+    BSGTruncateContext context = (BSGTruncateContext){.maxLength = 3};
+    XCTAssertEqualObjects(BSGTruncateStrings(&context, @{@"name": @"foo bar"}),
+                          @{@"name": @"foo"
+                            "\n***4 CHARS TRUNCATED***"});
+    XCTAssertEqual(context.strings, 1);
+    XCTAssertEqual(context.length, 4);
+}
+
+- (void)testTruncateStringsWithNestedObjects {
+    BSGTruncateContext context = (BSGTruncateContext){.maxLength = 3};
+    XCTAssertEqualObjects(BSGTruncateStrings(&context, (@{@"one": @{@"key": @"foo bar"},
+                                                          @"two": @{@"foo": @"Baa, Baa, Black Sheep"}})),
+                          (@{@"one": @{@"key": @"foo"
+                                       "\n***4 CHARS TRUNCATED***"},
+                             @"two": @{@"foo": @"Baa"
+                                       "\n***18 CHARS TRUNCATED***"}}));
+    XCTAssertEqual(context.strings, 2);
+    XCTAssertEqual(context.length, 22);
+}
+
+@end
diff --git a/Tests/BugsnagTests/BugsnagConfigurationTests.m b/Tests/BugsnagTests/BugsnagConfigurationTests.m
index ed9c31937..2f7108f02 100644
--- a/Tests/BugsnagTests/BugsnagConfigurationTests.m
+++ b/Tests/BugsnagTests/BugsnagConfigurationTests.m
@@ -650,6 +650,7 @@ - (void)testDefaultConfigurationValues {
     XCTAssertEqualObjects(@"https://notify.bugsnag.com", config.endpoints.notify);
     XCTAssertEqualObjects(@"https://sessions.bugsnag.com", config.endpoints.sessions);
     XCTAssertEqual(50, config.maxBreadcrumbs);
+    XCTAssertEqual(config.maxStringValueLength, 10000);
     XCTAssertTrue(config.persistUser);
     XCTAssertEqual(1, [config.redactedKeys count]);
     XCTAssertEqualObjects(@"password", [config.redactedKeys allObjects][0]);
@@ -872,6 +873,7 @@ - (void)testNSCopying {
 #if !TARGET_OS_WATCH
     [config setSendThreads:BSGThreadSendPolicyUnhandledOnly];
 #endif
+    [config setMaxStringValueLength:100];
     [config addPlugin:(id)[NSNull null]];
 
     BugsnagOnSendErrorBlock onSendBlock1 = ^BOOL(BugsnagEvent * _Nonnull event) { return true; };
@@ -928,6 +930,8 @@ - (void)testNSCopying {
     // Plugins
     XCTAssert([clone.plugins containsObject:[NSNull null]]);
     XCTAssertNoThrow([clone.plugins removeObject:[NSNull null]]);
+    
+    XCTAssertEqual(clone.maxStringValueLength, 100);
 }
 
 - (void)testMetadataMutability {
diff --git a/Tests/BugsnagTests/BugsnagEventTests.m b/Tests/BugsnagTests/BugsnagEventTests.m
index 0e337604d..e163f74a1 100644
--- a/Tests/BugsnagTests/BugsnagEventTests.m
+++ b/Tests/BugsnagTests/BugsnagEventTests.m
@@ -321,6 +321,58 @@ - (void)testJsonToEventToJson {
     }
 }
 
+- (void)testTruncateStrings {
+    BugsnagEvent *event = [BugsnagEvent new];
+    
+    BugsnagBreadcrumb * (^ MakeBreadcrumb)() = ^(NSString *message) {
+        BugsnagBreadcrumb *breadcrumb = [BugsnagBreadcrumb new];
+        breadcrumb.message = message;
+        breadcrumb.metadata = @{@"string": message};
+        return breadcrumb;
+    };
+    
+    event.breadcrumbs = @[
+        MakeBreadcrumb(@"Lorem ipsum dolor si"
+        "t amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua."),
+        
+        MakeBreadcrumb(@"Lorem ipsum is place"
+        "holder text commonly used in the graphic, print, and publishing industries for previewing layouts and visual mockups."),
+        
+        MakeBreadcrumb(@"20 characters string")];
+    
+    event.metadata = [[BugsnagMetadata alloc] initWithDictionary:@{}];
+    [event addMetadata:@"From its medieval or"
+     "igins to the digital era, learn everything there is to know about the ubiquitous lorem ipsum passage."
+               withKey:@"name" toSection:@"test"];
+    
+    event.usage = @{}; // Enable gathering telemetry
+    
+    [event truncateStrings:20];
+    
+    XCTAssertEqualObjects([event.usage valueForKeyPath:@"system.stringsTruncated"], @5);
+    
+    XCTAssertEqualObjects([event.usage valueForKeyPath:@"system.stringCharsTruncated"], @(103 + 103 + 117 + 117 + 101));
+    
+    XCTAssertEqualObjects(event.breadcrumbs[0].message, @"Lorem ipsum dolor si"
+                          "\n***103 CHARS TRUNCATED***");
+    
+    XCTAssertEqualObjects(event.breadcrumbs[0].metadata[@"string"], @"Lorem ipsum dolor si"
+                          "\n***103 CHARS TRUNCATED***");
+    
+    XCTAssertEqualObjects(event.breadcrumbs[1].message, @"Lorem ipsum is place"
+                          "\n***117 CHARS TRUNCATED***");
+    
+    XCTAssertEqualObjects(event.breadcrumbs[1].metadata[@"string"], @"Lorem ipsum is place"
+                          "\n***117 CHARS TRUNCATED***");
+    
+    XCTAssertEqualObjects(event.breadcrumbs[2].message, @"20 characters string");
+    
+    XCTAssertEqualObjects(event.breadcrumbs[2].metadata[@"string"], @"20 characters string");
+    
+    XCTAssertEqualObjects([event getMetadataFromSection:@"test" withKey:@"name"], @"From its medieval or"
+                          "\n***101 CHARS TRUNCATED***");
+}
+
 // MARK: - Feature flags interface
 
 - (void)testFeatureFlags {
@@ -679,4 +731,5 @@ - (void)testRuntimeVersionsUnhandled {
     };
     XCTAssertEqualObjects(expected, event.device.runtimeVersions);
 }
+
 @end
diff --git a/features/barebone_tests.feature b/features/barebone_tests.feature
index ddb4dda96..d041456e1 100644
--- a/features/barebone_tests.feature
+++ b/features/barebone_tests.feature
@@ -63,6 +63,7 @@ Feature: Barebone tests
     And the event "metaData.Exception.info" equals "Some error specific information"
     And the event "metaData.Flags.Testing" is true
     And the event "metaData.Other.password" equals "[REDACTED]"
+    And the event "metaData.Other.shouldBeTruncated" matches "\n\*\*\*345 CHARS TRUNCATED\*\*\*"
     And the event "metaData.error.nsexception.name" equals "NSRangeException"
     And the event "metaData.error.nsexception.userInfo.date" equals "2001-01-01 00:00:00 +0000"
     And the event "metaData.error.nsexception.userInfo.NSUnderlyingError" matches "Error Domain=ErrorDomain Code=0"
@@ -88,6 +89,8 @@ Feature: Barebone tests
       | ios     | true  |
       | macos   | @null |
       | watchos | @null |
+    And the event "usage.system.stringCharsTruncated" equals 345
+    And the event "usage.system.stringsTruncated" equals 1
     And the event "user.email" equals "foobar@example.com"
     And the event "user.id" equals "foobar"
     And the event "user.name" equals "Foo Bar"
diff --git a/features/fixtures/shared/scenarios/BareboneTestHandledScenario.swift b/features/fixtures/shared/scenarios/BareboneTestHandledScenario.swift
index b6a06cc58..763a83822 100644
--- a/features/fixtures/shared/scenarios/BareboneTestHandledScenario.swift
+++ b/features/fixtures/shared/scenarios/BareboneTestHandledScenario.swift
@@ -42,6 +42,7 @@ class BareboneTestHandledScenario: Scenario {
         config.addMetadata(["Testing": true], section: "Flags")
         config.addMetadata(["password": "123456"], section: "Other")
         config.launchDurationMillis = 0
+        config.maxStringValueLength = 100
 #if !os(watchOS)
         config.sendThreads = .unhandledOnly
 #endif
@@ -78,6 +79,15 @@ class BareboneTestHandledScenario: Scenario {
         
         self.afterSendErrorBlock = self.afterSendError
         
+        Bugsnag.addMetadata("""
+            Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod \
+            tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, \
+            quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. \
+            Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu \
+            fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in \
+            culpa qui officia deserunt mollit anim id est laborum.
+            """, key: "shouldBeTruncated", section: "Other")
+        
         Bugsnag.notify(NSException(name: .rangeException,
                                    reason: "-[__NSSingleObjectArrayI objectAtIndex:]: index 1 beyond bounds [0 .. 0]",
                                    userInfo: ["date": Date(timeIntervalSinceReferenceDate: 0),
diff --git a/features/fixtures/shared/scenarios/OversizedCrashReportScenario.swift b/features/fixtures/shared/scenarios/OversizedCrashReportScenario.swift
index a1478eaf1..57dfd6e78 100644
--- a/features/fixtures/shared/scenarios/OversizedCrashReportScenario.swift
+++ b/features/fixtures/shared/scenarios/OversizedCrashReportScenario.swift
@@ -3,6 +3,7 @@ class OversizedCrashReportScenario: Scenario {
     override func startBugsnag() {
         config.autoTrackSessions = false
         config.enabledErrorTypes.ooms = false
+        config.maxStringValueLength = UInt.max
         config.addOnSendError {
             var data = Data(count: 1024 * 1024)
             _ = data.withUnsafeMutableBytes {
diff --git a/features/fixtures/shared/scenarios/OversizedHandledErrorScenario.swift b/features/fixtures/shared/scenarios/OversizedHandledErrorScenario.swift
index efd783a24..414e6251c 100644
--- a/features/fixtures/shared/scenarios/OversizedHandledErrorScenario.swift
+++ b/features/fixtures/shared/scenarios/OversizedHandledErrorScenario.swift
@@ -3,6 +3,7 @@ class OversizedHandledErrorScenario: Scenario {
     override func startBugsnag() {
         config.autoTrackSessions = false
         config.enabledErrorTypes.ooms = false
+        config.maxStringValueLength = UInt.max
         config.addOnSendError {
             var data = Data(count: 1024 * 1024)
             _ = data.withUnsafeMutableBytes {