API Tester Help

Environment

No request selected

Create a collection in the sidebar, then add a request. Use {{variable}} placeholders in URLs, headers, params and the request body to substitute values from the active environment.

Description

Query parameters are kept in sync with the URL. Use {{var}} for substitution.

Standard HTTP headers. The browser may add/override Origin, User-Agent, Cookie, etc. for CORS reasons.

Quick add:

none JSON raw x-www-form-urlencoded form-data (text only)

Type

The request after variable substitution. This is exactly what gets sent.

cURL equivalent:

Response — send a request to see response —

Pretty Raw

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Instructions & Help

Overview

API Tester lets you build, save and replay HTTP requests. Collections, requests and environments are stored in IndexedDB inside your browser — nothing is uploaded.

Collections & requests

New collection: click + Collection in the sidebar.
New request: hover a collection, click its + button. The new request opens in the editor — give it a URL and hit Save.
Rename / duplicate / delete: use the collection menu (⋮) or the toolbar inside the request editor.
Copy / cut / paste: use the menu (⋮) next to a request to copy or cut it, then paste into any collection from that collection's menu.

Variables

Anywhere a string is used (URL, headers, params, body), {{name}} is substituted at send time.
Environments are named bundles of variables. The header dropdown selects which one is active.
Global variables are used as a fallback when a variable isn't in the active environment.
Use the Preview tab on a request to see the final, substituted request and its cURL equivalent.

Body modes

JSON — sets Content-Type: application/json automatically if you haven't set one. Pretty-formats with the Pretty button.
raw — exactly the text you type. You set the Content-Type header.
x-www-form-urlencoded — key/value table, encoded into the body.
form-data (text only) — multipart form, text fields. File uploads aren't supported in v1.

Importing OpenAPI / Swagger / Postman

Import spec… opens a wizard. Pick one of the bundled popular OpenAPI specs, type a URL, pick a JSON file, or paste the document directly.
Auto-detects OpenAPI 3.x, Swagger 2.0, and Postman v2.x.
Path parameters ({id} in OpenAPI, :id in Postman) are rewritten to {{id}} so you can set them via the active environment.
Query and header parameters become rows in the request — required ones are enabled, optional ones unchecked.
Request bodies are pre-filled from the schema (using example fields when present).
Postman folders are flattened with the folder name as a prefix on each request. Postman collection variables become an environment named after the collection.
Postman auth (bearer, basic, apikey) maps to our auth tab. Other auth types fall back to "none" — set headers manually.
If a remote URL fails with a CORS error, open it in a normal browser tab and paste the JSON.

Descriptions

Every collection has a description, edited via the ⋮ menu → Edit collection….
Every request has a description, edited in the collapsible Description section at the top of the editor.
A bullet appears next to the section title when a description exists.

Backup & restore

Export in the header writes a JSON file containing every collection, request and environment.
Import reads that file. You can either replace everything or merge — duplicates by name become "(copy)".
Data also rides along with the central site data tool, so a single export there will back up every tool at once.

CORS & what the browser allows

This tool uses the browser's fetch. If the target server doesn't send permissive CORS headers, the request will fail with a CORS error and you won't be able to read the response.
Some headers (Origin, Cookie, User-Agent, Host) cannot be set from a browser — use a desktop tool for those.
For local development, calling http://localhost APIs typically works fine.

No request selected

Variables & Environments

Global variables (used when no environment selected, or as a fallback)

Environments

Import collection

Source

Preview

Title

Edit collection