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name mock-response
description Build a shareable mock HTTP response URL using the Secutils.dev echo tool - given a status code, headers, body, and optional description, encode the state and emit https://tools.secutils.dev/echo#{encoded} (configurator) or https://tools.secutils.dev/echo?c={encoded} (served mock). Trigger when the user asks for a "mock response", "echo URL", "fake HTTP response", "test response URL", or anything that names secutils.dev/echo.

Mock response (Secutils.dev echo)

Produce a URL that opens (or serves, with ?c=) a mock HTTP response on the Secutils.dev echo responder. State is round-tripped through the URL itself; no account or API call is involved.

Inputs

Field Type Default Notes
description string "" Free-text label, kept in URL, not sent to clients.
status int 100–599 200 Clamp out-of-range values.
headers array of [name, value] [] Drop entries with empty name. Responder auto-adds Content-Type: text/plain; charset=utf-8 if no Content-Type is set.
body string "" Pass-through. Do not JSON-stringify the user's body - they want literal bytes.

State object shape (keys are exactly d, s, h, b, in that order):

{"d":"<description>","s":<status>,"h":[["Header","Value"], ...],"b":"<body>"}

Wire format

After URL-safe base64 decoding:

| 4 bytes uncompressed-length (LE u32) | N bytes raw DEFLATE of UTF-8 JSON |

Pipeline: JSON.stringify(state) → UTF-8 bytes → deflate-raw → prepend the 4-byte LE u32 of the uncompressed length → base64url (+→-, /→_, strip =).

How to produce the URL

Run this on any machine with Node ≥ 18 (no deps):

node -e '
const zlib = require("node:zlib");
const state = JSON.parse(process.argv[1]);
const utf8 = Buffer.from(JSON.stringify(state), "utf8");
const out = Buffer.concat([Buffer.alloc(4), zlib.deflateRawSync(utf8)]);
out.writeUInt32LE(utf8.length, 0);
const enc = out.toString("base64").replace(/\+/g,"-").replace(/\//g,"_").replace(/=+$/,"");
console.log("https://tools.secutils.dev/echo#" + enc);
' '{"d":"my desc","s":200,"h":[["Content-Type","text/html; charset=utf-8"]],"b":"Hello!"}'

Pass the state as the first argv (single-quoted JSON) so embedded quotes, newlines, and shell metacharacters survive untouched. Always print the full URL - the fragment is opaque and dropping a single character breaks decoding.

For the served-mock URL (responder inflates and replays), swap # for ?c= - same encoded blob.

Producing the URL inline (no Node available)

The encoding is small enough to do in any language with a deflate library - Python (zlib.compress(..., wbits=-15)), Rust (flate2::write::DeflateEncoder), etc. Identical wire format. The byte-exact compressed output varies across deflate implementations; that's fine - the responder uses tiny-inflate, which accepts any valid raw-deflate stream.

After producing

Hand the URL back verbatim in a fenced block or inline code so the user can copy it cleanly. One sentence summary at most. Don't paraphrase the body or abbreviate the fragment.

Caveats

  • description is for humans reading the share link - never include secrets; the fragment is visible to anyone with the URL (though never sent to the server when used with #, only with ?c=).
  • For HTML/JSON bodies, set Content-Type explicitly - the auto-injected default is text/plain; charset=utf-8.
  • ?c= shape is for the served mock and the fragment is browser-side only; use # when the user wants to land on the configurator UI with state pre-filled.