README
¶
Kasper
HTTP toolkit for Go. Drop-in gorilla/mux replacement with WebSocket, OpenAPI, and middleware support. Inspired by FastAPI.
go get github.com/vitalvas/kasper
Requires Go 1.25+.
mux
HTTP request multiplexer. API-compatible with gorilla/mux.
| Feature | Details |
|---|---|
| Path variables | Regex constraints and macros: uuid, int, float, slug, alpha, alphanum, date, hex, domain |
| Matchers | Host, method, header, query, scheme, custom MatcherFunc |
| Routing | Subrouters, middleware, named routes, URL building |
| Request/Response | BindJSON, BindXML, ResponseJSON, ResponseXML |
| Standards | Strict slash (RFC 7538), path cleaning (RFC 3986), route walking |
websocket
RFC 6455 / RFC 8441 WebSocket implementation.
| Feature | Details |
|---|---|
| Connections | Client (Dialer) and server (Upgrader) |
| Messaging | Text/binary, streaming (NextReader/NextWriter), JSON helpers |
| Control | Ping, pong, close frames, subprotocol negotiation |
| Compression | permessage-deflate (RFC 7692), stateless |
| Performance | PreparedMessage for broadcasting, BufferPool for buffer reuse |
| Network | Proxy support (HTTP CONNECT) |
openapi
Automatic OpenAPI v3.1.0 spec generation from mux routes via reflection and struct tags.
| Feature | Details |
|---|---|
| Schema | JSON Schema Draft 2020-12, struct tags (openapi:"format=email,minLength=1"), Namer/Exampler interfaces |
| Routes | Named routes (Op), direct attachment (Route), groups for shared metadata |
| Security | Basic, bearer, OAuth2, API key schemes |
| Content | Webhooks, callbacks, multiple content types, generic type support |
| Docs UI | Swagger UI, RapiDoc, Redoc |
| Export | doc.JSON(), doc.YAML(), JSON/YAML schema endpoints |
| Parsing | DocumentFromJSON, DocumentFromYAML |
| Merge | MergeDocuments combines multiple specs with conflict detection |
| Standalone | SchemaGenerator.Document produces a spec without a mux router |
httpsig
HTTP Message Signatures (RFC 9421) with optional Content-Digest (RFC 9530).
| Feature | Standard | Details |
|---|---|---|
| Signing | RFC 9421 | SignRequest adds Signature and Signature-Input headers |
| Verification | RFC 9421 | VerifyRequest with key resolver, max age, required components |
| Client Transport | RFC 9421 | http.RoundTripper for automatic request signing |
| Server Middleware | RFC 9421 | mux.MiddlewareFunc for automatic request verification |
| Content-Digest | RFC 9530 | SHA-256/SHA-512 body digest generation and verification |
| Algorithms | RFC 9421 | Ed25519, ECDSA P-256/P-384, RSA-PSS, RSA v1.5, HMAC-SHA256 |
muxhandlers
HTTP middleware for the mux router.
| Middleware | Standard | Details |
|---|---|---|
CORSMiddleware |
Fetch Standard | Origin validation, preflight, wildcard/subdomain patterns |
BasicAuthMiddleware |
RFC 7617 | Static or dynamic credentials, constant-time comparison |
ProxyHeadersMiddleware |
RFC 7239 | X-Forwarded-For/Proto/Host, Forwarded header, trusted proxy validation |
RecoveryMiddleware |
-- | Panic recovery, 500 response, optional log callback |
RequestIDMiddleware |
RFC 9562 | UUID v4/v7 generation/propagation via X-Request-ID header |
RequestSizeLimitMiddleware |
-- | Body size enforcement via http.MaxBytesReader, 413 on excess |
TimeoutMiddleware |
-- | Handler execution time limit via http.TimeoutHandler, 503 on timeout |
CompressionMiddleware |
-- | Gzip/deflate response compression with sync.Pool, quality-based encoding selection, min-length threshold |
SecurityHeadersMiddleware |
-- | X-Content-Type-Options, X-Frame-Options, Referrer-Policy, HSTS, CSP, Permissions-Policy |
MethodOverrideMiddleware |
-- | HTTP method override via configurable header, POST-only, allowed method validation |
ContentTypeCheckMiddleware |
-- | Content-Type validation with case-insensitive matching, parameter-ignoring, 415 on mismatch |
ServerMiddleware |
-- | Sets X-Server-Hostname response header, resolved once via os.Hostname or static value |
CacheControlMiddleware |
-- | Sets Cache-Control and Expires response headers based on Content-Type prefix rules, case-insensitive matching |
StaticFilesHandler |
-- | Serves static files from any fs.FS via http.FileServerFS, directory listing disabled by default, SPA fallback support |
Directories
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| Path | Synopsis |
|---|---|
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examples
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openapi
command
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openapi_simple
command
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Package httpsig implements HTTP Message Signatures per RFC 9421 with optional Content-Digest support per RFC 9530.
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Package httpsig implements HTTP Message Signatures per RFC 9421 with optional Content-Digest support per RFC 9530. |
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Package mux implements a request router and dispatcher for matching incoming HTTP requests to their respective handler functions.
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Package mux implements a request router and dispatcher for matching incoming HTTP requests to their respective handler functions. |
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Package muxhandlers provides HTTP middleware handlers for the mux router.
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Package muxhandlers provides HTTP middleware handlers for the mux router. |
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Package openapi provides automatic OpenAPI v3.1.0 specification generation from mux router routes using Go reflection and struct tags.
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Package openapi provides automatic OpenAPI v3.1.0 specification generation from mux router routes using Go reflection and struct tags. |
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Compression support for WebSocket permessage-deflate extension (RFC 7692).
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Compression support for WebSocket permessage-deflate extension (RFC 7692). |
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