API documentation

HTTP request and response testing: decode base64, echo requests, return custom status codes, set headers, test redirects and stream responses.

Base URL: https://httpresponder.com. Public access with no accounts, API keys or application rate limits. All APIs support cross-origin requests. Use the OpenAPI specification for machine-readable request and response schemas.

Send POST bodies as JSON or URL-encoded form data unless an endpoint specifies a raw body. Prefer POST for sensitive content. Errors return JSON with error.code and error.message. See the usage notes for request bounds and usage notes.

`GET /base64`

Decode standard or URL-safe base64, or encode UTF-8 with mode=encode. POST text/plain also accepted.

data query: Input data.
mode query: Operation. Default: "decode". Allowed: decode, encode.
content_type query: Decoded response media type. Default: "text/plain; charset=utf-8".

`POST /base64`

Decode standard or URL-safe base64, or encode UTF-8 with mode=encode. POST text/plain also accepted.

data body: Input data.
mode body: Operation. Default: "decode". Allowed: decode, encode.
content_type body: Decoded response media type. Default: "text/plain; charset=utf-8".

`GET /base64/{encoded}`

Decode base64 from the URL path. URL-safe base64 recommended.

encoded path · required: Base64 payload.
content_type query: Decoded response media type.

`GET /respond`

Return a custom body, status, headers and optional delay. HTML can execute JavaScript in an isolated origin.

status query: HTTP status. Default: 200.
body query: Response body.
base64 query: Binary body as base64; takes precedence over body.
content_type query: Media type. Default: "text/plain; charset=utf-8".
headers query: For GET, pass JSON-encoded headers.
delay query: number Default: 0.

`POST /respond`

Return a custom body, status, headers and optional delay. HTML can execute JavaScript in an isolated origin.

status body: HTTP status. Default: 200.
body body: Response body.
base64 body: Binary body as base64; takes precedence over body.
content_type body: Media type. Default: "text/plain; charset=utf-8".
headers body: For GET, pass JSON-encoded headers.
delay body: number Default: 0.

`GET /mix/{directives}`

Combine /s=201/h=content-type:text%2Fplain/b64=SGVsbG8=. Supports s,h,c,r,b64,end; Go templates are not supported.

directives path · required: Slash-separated directives. URL-encode values containing slashes.

`GET /get`

Echo method, query, headers, body, parsed JSON, form fields and multipart files.

`POST /post`

Echo method, query, headers, body, parsed JSON, form fields and multipart files.

`PUT /put`

Echo method, query, headers, body, parsed JSON, form fields and multipart files.

`PATCH /patch`

Echo method, query, headers, body, parsed JSON, form fields and multipart files.

`DELETE /delete`

Echo method, query, headers, body, parsed JSON, form fields and multipart files.

`GET /anything`

HTTP diagnostic endpoint. Echo, headers, payload, and cookies accept any method.

`POST /anything`

Echo posted request.

`GET /any`

HTTP diagnostic endpoint. Echo, headers, payload, and cookies accept any method.

`POST /any`

Echo posted request.

`GET /payload`

HTTP diagnostic endpoint. Echo, headers, payload, and cookies accept any method.

`POST /payload`

Echo posted request.

`GET /headers`

HTTP diagnostic endpoint. Echo, headers, payload, and cookies accept any method.

`GET /ip`

HTTP diagnostic endpoint. Echo, headers, payload, and cookies accept any method.

`GET /user-agent`

HTTP diagnostic endpoint. Echo, headers, payload, and cookies accept any method.

`GET /uuid`

HTTP diagnostic endpoint. Echo, headers, payload, and cookies accept any method.

`GET /cookies`

HTTP diagnostic endpoint. Echo, headers, payload, and cookies accept any method.

`GET /bearer`

HTTP diagnostic endpoint. Echo, headers, payload, and cookies accept any method.

`GET /json`

HTTP diagnostic endpoint. Echo, headers, payload, and cookies accept any method.

`GET /html`

HTTP diagnostic endpoint. Echo, headers, payload, and cookies accept any method.

`GET /xml`

HTTP diagnostic endpoint. Echo, headers, payload, and cookies accept any method.

`GET /gzip`

HTTP diagnostic endpoint. Echo, headers, payload, and cookies accept any method.

`GET /deflate`

HTTP diagnostic endpoint. Echo, headers, payload, and cookies accept any method.

`GET /status/{codes}`

Return a status (200–599).

codes path · required: One status or a comma-separated list.

`GET /delay/{seconds}`

Delay then echo.

seconds path · required: number

`GET /bytes/{count}`

Generate random bytes.

count path · required: Random bytes.

`GET /stream/{count}`

Stream NDJSON records.

count path · required: NDJSON records.

`GET /redirect/{count}`

Redirect repeatedly then echo.

count path · required: Redirect count.

`GET /relative-redirect/{count}`

Relative redirects.

count path · required: Redirect count.

`GET /absolute-redirect/{count}`

Absolute redirects.

count path · required: Redirect count.

`GET /cache/{age}`

Cache-Control and conditional requests.

age path · required: Max age in seconds.

`GET /etag/{etag}`

If-Match and If-None-Match support.

etag path · required: Entity tag without quotes.

`GET /response-headers`

Return all query parameters as response headers (runtime hop-by-hop headers excluded).

`GET /redirect-to`

Redirect to HTTP(S) or a relative path.

url query · required: Public HTTP(S) destination.
status_code query: 301,302,303,307,308. Default: 302.

`GET /basic-auth/{username}/{password}`

Test HTTP Basic auth.

username path · required: Username.
password path · required: Password.

`GET /bearer/{expectedToken}`

Test Bearer auth.

expectedToken path · required: Expected token.

`GET /cookies/set`

Query parameters supply cookie names and values.

`GET /cookies/delete`

Query parameters supply cookie names and values.

`GET /drip`

Stream bytes or server-sent events. Total duration plus delay <=10 seconds.

duration query: number
delay query: number
numbytes query: Drip count. Default: 10.
count query: SSE events. Default: 5.
code query: HTTP status. Default: 200.

`GET /drip-lines`

Stream bytes or server-sent events. Total duration plus delay <=10 seconds.

duration query: number
delay query: number
numbytes query: Drip count. Default: 10.
count query: SSE events. Default: 5.
code query: HTTP status. Default: 200.

`GET /sse`

Stream bytes or server-sent events. Total duration plus delay <=10 seconds.

duration query: number
delay query: number
numbytes query: Drip count. Default: 10.
count query: SSE events. Default: 5.
code query: HTTP status. Default: 200.

`GET /links/{count}/{offset}`

Generate linked HTML.

count path · required: Links.
offset path · required: Current link.

`GET /docs`

Server-rendered HTML API reference.

`GET /robots.txt`

Crawler access rules and sitemap location.

`GET /sitemap.xml`

Public documentation sitemap.

`GET /health`

Worker liveness (does not probe external dependencies).

`GET /llms.txt`

Plain-text agent usage guide.