diff --git a/conda_build/build.py b/conda_build/build.py
index 81fb526011..b64ea641dd 100644
--- a/conda_build/build.py
+++ b/conda_build/build.py
@@ -2607,6 +2607,7 @@ def build(
 
         utils.rm_rf(m.config.info_dir)
         files1 = utils.prefix_files(prefix=m.config.host_prefix)
+        os.makedirs(m.config.build_folder, exist_ok=True)
         with open(join(m.config.build_folder, "prefix_files.txt"), "w") as f:
             f.write("\n".join(sorted(list(files1))))
             f.write("\n")
diff --git a/conda_build/environ.py b/conda_build/environ.py
index 853da44e02..7ef1b2a33d 100644
--- a/conda_build/environ.py
+++ b/conda_build/environ.py
@@ -580,7 +580,7 @@ def get_shlib_ext(host_platform):
         return ".dll"
     elif host_platform in ["osx", "darwin"]:
         return ".dylib"
-    elif host_platform.startswith("linux"):
+    elif host_platform.startswith("linux") or host_platform.endswith("-wasm32"):
         return ".so"
     elif host_platform == "noarch":
         # noarch packages should not contain shared libraries, use the system
diff --git a/conda_build/metadata.py b/conda_build/metadata.py
index 33c3230573..47f3166727 100644
--- a/conda_build/metadata.py
+++ b/conda_build/metadata.py
@@ -124,14 +124,17 @@ def get_selectors(config: Config) -> dict[str, bool]:
         linux=plat.startswith("linux-"),
         linux32=bool(plat == "linux-32"),
         linux64=bool(plat == "linux-64"),
+        emscripten=plat.startswith("emscripten-"),
+        wasi=plat.startswith("wasi-"),
         arm=plat.startswith("linux-arm"),
         osx=plat.startswith("osx-"),
-        unix=plat.startswith(("linux-", "osx-")),
+        unix=plat.startswith(("linux-", "osx-", "emscripten-")),
         win=plat.startswith("win-"),
         win32=bool(plat == "win-32"),
         win64=bool(plat == "win-64"),
         x86=plat.endswith(("-32", "-64")),
         x86_64=plat.endswith("-64"),
+        wasm32=bool(plat.endswith("-wasm32")),
         os=os,
         environ=os.environ,
         nomkl=bool(int(os.environ.get("FEATURE_NOMKL", False))),
diff --git a/conda_build/utils.py b/conda_build/utils.py
index aa375790f3..989cf0dba4 100644
--- a/conda_build/utils.py
+++ b/conda_build/utils.py
@@ -113,6 +113,8 @@ def glob(pathname, recursive=True):
 mmap_PROT_WRITE = 0 if on_win else mmap.PROT_WRITE
 
 DEFAULT_SUBDIRS = {
+    "emscripten-wasm32",
+    "wasi-wasm32",
     "linux-64",
     "linux-32",
     "linux-s390x",
diff --git a/news/4813-wasm-platforms b/news/4813-wasm-platforms
new file mode 100644
index 0000000000..1dd82f5479
--- /dev/null
+++ b/news/4813-wasm-platforms
@@ -0,0 +1,19 @@
+### Enhancements
+
+* Handle `emscripten-wasm32` and `wasi-wasm32` platforms. (#4813)
+
+### Bug fixes
+
+* <news item>
+
+### Deprecations
+
+* <news item>
+
+### Docs
+
+* <news item>
+
+### Other
+
+* <news item>
diff --git a/tests/test_api_skeleton.py b/tests/test_api_skeleton.py
index 10d9a6973e..514d469c56 100644
--- a/tests/test_api_skeleton.py
+++ b/tests/test_api_skeleton.py
@@ -28,13 +28,19 @@
 from conda_build.utils import on_win
 from conda_build.version import _parse as parse_version
 
-SYMPY_URL = "https://pypi.python.org/packages/source/s/sympy/sympy-1.10.tar.gz#md5=b3f5189ad782bbcb1bedc1ec2ca12f29"
+SYMPY_URL = (
+    "https://files.pythonhosted.org/packages/7d/23/70fa970c07f0960f7543af982d2554be805e1034b9dcee9cb3082ce80f80/sympy-1.10.tar.gz"
+    "#sha256=6cf85a5cfe8fff69553e745b05128de6fc8de8f291965c63871c79701dc6efc9"
+)
 
 PYLINT_VERSION = "2.3.1"
 PYLINT_HASH_TYPE = "sha256"
 PYLINT_HASH_VALUE = "723e3db49555abaf9bf79dc474c6b9e2935ad82230b10c1138a71ea41ac0fff1"
+PYLINT_HASH_VALUE_BLAKE2 = (
+    "018b538911c0ebc2529f15004f4cb07e3ca562bb9aacea5df89cc25b62e01891"
+)
 PYLINT_FILENAME = f"pylint-{PYLINT_VERSION}.tar.gz"
-PYLINT_URL = f"https://pypi.python.org/packages/source/p/pylint/{PYLINT_FILENAME}#{PYLINT_HASH_TYPE}={PYLINT_HASH_VALUE}"
+PYLINT_URL = f"https://files.pythonhosted.org/packages/{PYLINT_HASH_VALUE_BLAKE2[:2]}/{PYLINT_HASH_VALUE_BLAKE2[2:4]}/{PYLINT_HASH_VALUE_BLAKE2[4:]}/{PYLINT_FILENAME}"
 
 
 @pytest.fixture