OpenAPI 3.0 / 3.1 / 3.2 to multi-language code generator
OpenAPI Nexus transforms OpenAPI specifications into type-safe client libraries. Generated output is deterministic, compile-checked in CI, and tested byte-for-byte via golden tests.
| Language | Generator | HTTP Client | Status |
|---|---|---|---|
| TypeScript | typescript-fetch |
fetch | Beta |
| Go | go-http |
net/http | Beta |
| Rust | rust-reqwest |
reqwest | Beta |
| Rust | rust-ureq |
ureq | Beta |
| Rust | rust-aioduct |
aioduct | Beta |
| Python | python-httpx |
httpx | Beta |
| Python | python-requests |
requests | Beta |
| Java | java-okhttp |
OkHttp | Beta |
| Kotlin | kotlin-okhttp |
OkHttp | Beta |
Shell installer (no Rust toolchain needed):
curl --proto '=https' --tlsv1.2 -LsSf https://github.com/rust-codegen-group/openapi-nexus/releases/download/0.2.0/openapi-nexus-installer.sh | shNightly build (latest main):
curl --proto '=https' --tlsv1.2 -LsSf https://github.com/rust-codegen-group/openapi-nexus/releases/download/nightly/openapi-nexus-installer.sh | shBuild from source:
cargo install openapi-nexusRequires Rust 1.90+.
# TypeScript client
openapi-nexus generate -i spec.yaml -o output --generators typescript-fetch
# Go client
openapi-nexus generate -i spec.yaml -o output --generators go-http
# Rust client (reqwest)
openapi-nexus generate -i spec.yaml -o output --generators rust-reqwest
# Python client (httpx)
openapi-nexus generate -i spec.yaml -o output --generators python-httpx
# Java client
openapi-nexus generate -i spec.yaml -o output --generators java-okhttp
# Generate another target into its own directory
openapi-nexus generate -i spec.yaml -o output/go --generators go-http
openapi-nexus generate -i spec.yaml -o output/rust --generators rust-reqwestConfiguration resolves in order: CLI args > environment variables (OPENAPI_NEXUS_*) > config file (openapi-nexus-config.toml) > defaults.
# Environment variables
export OPENAPI_NEXUS_INPUT="spec.yaml"
export OPENAPI_NEXUS_OUTPUT="generated"
export OPENAPI_NEXUS_GENERATORS="typescript-fetch"Generator-specific options go in the config file:
[generators.go-http]
module_path = "github.com/myorg/myproject/sdk"
[generators.rust-reqwest]
workspace_mode = true
workspace_deps = "workspace_version"
[generators.rust-reqwest.extra_derives.structs]
derives = ["PartialEq"]
[generators.rust-reqwest.extra_derives.enums]
derives = ["Hash"]
[generators.rust-reqwest.utoipa]
enabled = true
dependency = '{ version = "5" }'
[generators.rust-aioduct.aioduct]
compression = ["gzip", "zstd"]
features = ["tracing"]
[generators.typescript-fetch]
emit_enum_constants = true
emit_type_guards = true
property_naming = "camelCase"OpenAPI YAML/JSON → parse → lower to IR → CodeGenerator::generate(&IrSpec) → write
Parsing auto-detects OAS version (3.0, 3.1, 3.2). Lowering produces a version-agnostic IrSpec. Each generator receives the pre-lowered IR and uses sigil-stitch for type-safe code emission.
Full documentation is available at the project docs site.
Examples live under examples/, including multipart file upload and raw binary body usage in examples/multipart-binary.
# Run all tests
cargo test
# Clippy (required before commit)
cargo clippy --all-targets --all-features -- -D warnings
# Update golden files after intentional output changes
UPDATE_GOLDEN=1 cargo test
# Compile-check generated output for all languages
just golden-build-allDual-licensed under MIT or Apache-2.0 at your option.