Destiny is a standalone lightweight web server that makes use of the latest Swift features to push performance to the limit of the language, and designed to be easy to use while keeping the binary size small.
It provides a router (which is used via a Swift Macro) that accepts middleware, redirects, routes, and route groups for processing requests.
Features like TLS/SSL, Web Sockets and embedded support are coming soon.
We provide a blueprint library, DestinyBlueprint, that lays out the API of Destiny's inner workings to perform optimally, empowering the developer to determine the data structures and types used (if you don't use the default implementations from DestinyDefaults).
- Custom hostname and port (Nov 8, 2024)
- Middleware and Routes (Nov 8, 2024)
- Register middleware/routes after starting server (Nov 8, 2024)
- Support multiple data representations (Nov 8, 2024)
- Routes with parameters (Nov 8, 2024)
- CORS (Dec 9, 2024 | static CORS needs a little more work)
- Configure settings via Command Line Arguments (Dec 11, 2024)
- Redirects (Dec 11, 2024 | dynamic redirects need a little more work)
- Hybrid Routes (Dec 24, 2024 | see ConditionalRouteResponderProtocol)
- Route Groups (Dec 27, 2024)
- Error Middleware (Dec 29, 2024 | see ErrorResponderProtocol)
- Case insensitive routes (Feb 19, 2025 | dynamic routes need a little more work)
- Routes with wildcards (Feb 19, 2025)
- Better handling of clients to unlock more throughput (Feb 23, 2025)
- Response streaming (Aug 2, 2025)
- Typed throws where applicable (Aug 3, 2025)
- Foundation-less (Aug 5, 2025)
- Swift 6 Language Mode (Aug 5, 2025)
- Cookies (Aug 9, 2025)
- Metric Middleware
- DocC Documentation
- Unit testing
- File Middleware
- Rate Limit Middleware
- Route queries
- Header parsing
- HTTP Pipelining
- Embedded support
- DocC Tutorials
- Cache Middleware
- Request body streaming
- Data Validation (form, POST, etc)
- Authentication
- OpenAPI support
- Tracing support
- TLS/SSL
- Web Sockets
- Native load balancing & clustering
- Support custom middleware & routes in the macro
- Support third-party macro expansions in the macro
List of techniques Destiny uses to push performance to the limits of the Swift Language.
Structs by default
To avoid heap allocation and pointer indirection
Noncopyable types
For better memory management and to avoid retain/release/ARC traffic
@inlinable annotation
To make sure we inline hot-paths as much as possible
Actor avoidance
To encourage better state management and data structures
InlineArrays
To avoid heap allocations (especially in hot-paths)
Concurrency
To maximize multi-core performance and support non-blocking operations
Macros
Unlocks compile-time optimizations for the router, routes, route groups responders, and middleware.
Most runtime optimizations come from here. This includes:
- auto generation of optimized enums, structs and functions (avoiding classes and existentials)
- perfect hashing for routes (if enabled & possible)
Parameter Packs
For compile-time array optimizations, reducing heap allocations and dynamic dispatch
Opaque types
To avoid dynamic dispatch, existentials and boxing (especially in hot-paths)
Generic parameters
Only where opaque types aren't applicable to avoid dynamic dispatch, existentials and boxing (especially in hot-paths)
Typed throws
To improve runtime performance and a step closer to support embedded; eliminates heap allocation, metadata and dynamic dispatch for error handling
Swift 6 Language Mode
To avoid data races by enforcing compile time data race safety
Code Generation
For tedious work and easier development
Minimal Dependencies
To reduce binary size, simplify development and give full control over implementation details to the developer
- no Foundation
- no SwiftNIO
Module Abstractions
To simplify and allow more control over development implementations
Benchmarks and performance profiling
To determine best data structures and techniques for optimal performance without sacrificing functionality
List of techniques Destiny wants to incorporate to push performance even further, not strictly Swift related.
- file descriptor pool
- connection pool
- optionally batch responses
- kqueue support
- io_uring support
Areas that Swift needs more development/support to unlock more performance at the language level.
~Copyabletypes in parameter packs (currentCopyablerequirement causes retain/release and ARC traffic)~Copyabletypes not being able to be used as atypealiasorassociatedtype
coming soon...
*and:<param name>= parameter**= catchall
- Libraries tested
- RandomHashTags/destiny v0.2.0 (this library)
- hummingbird-project/hummingbird v2.11.1
- vapor/vapor v4.114.1
Initial testing of a basic HTML response shows this library has the lowest server latency, highest throughput and most consistent timings when serving the same content.
Depends on how much dynamic content you add; initial testing compared to a Static response performs about the same but usually costs a few microseconds more (~10-50). I am actively researching and testing improvements.
This library is a clear leader in reliability, performance and efficiency. Performance metrics for static and dynamic content are better than or comparable to the best networking libraries available (regardless of programming language).
Create a PR.
You can create a discussion here on GitHub for support or join my Discord server at https://discord.com/invite/VyuFQUpcUz.
This project was developed to allow everyone to create better http servers. I develop and maintain many free open-source projects full-time for the benefit of everyone.
You can show your financial appreciation for this project and others by sponsoring us here on GitHub or other ways listed in the FUNDING.yml.
