API documentation

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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. 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.