Convert4Me API

Every tool on this site is also available as one GET request. No sign-up, no API key, answers in JSON, and CORS is open, so it works from a browser, a server or an edge function. 72 endpoints: case converters, text tools, developer tools, generators and calculators.

No key, no sign-up

Just send the request. Nothing to register and nothing to rotate.

CORS enabled

Call it directly from front-end code. GET, HEAD and OPTIONS are allowed from any origin.

Same results as the website

The API is tested against the website's own code on hundreds of cases.

Quick start

The base URL is https://api.convert4me.com/api/v1. Add the tool name and its inputs as query parameters:

curl -G 'https://api.convert4me.com/api/v1/uppercase' --data-urlencode 'text=hello world'

Response, status 200:

{
  "ok": true,
  "tool": "uppercase",
  "action": "upper",
  "result": "HELLO WORLD"
}

From a web page:

const q = new URLSearchParams({ text: "hello world" });
const { result } = await fetch("https://api.convert4me.com/api/v1/uppercase?" + q).then((r) => r.json());

Responses and errors

Successful answers have "ok": true and the data next to it. Anything wrong with the request gives a 4xx status and a JSON body that says what to fix:

Status 400

{
  "ok": false,
  "error": {
    "code": "missing_parameter",
    "message": "Missing required parameter 'text'.",
    "param": "text"
  }
}

400 a parameter is missing or invalid, 404 unknown tool, 405 only GET, HEAD and OPTIONS are allowed.
413 a text value is over 6,000 characters, 414 the whole address is over 8,000 characters.
Add format=text to text tools to get the plain result instead of JSON.

Good to know

Fair use. There is no key and no quota, but this is a free service. Heavy automated use may be slowed or blocked to keep it free for everyone. Cache answers on your side.
Privacy. Unlike the website, the API receives your input in the request address. Do not send passwords or personal data. See the Privacy Policy.
Caching. The same request gives the same answer (except random generators and date-based tools), so responses are safe to cache.
Calculators give general information, not financial, tax or medical advice. Rates and rules are the same tables the website uses.
Machine-readable. OpenAPI 3 description for code generators and Postman, and a JSON list of all tools.

Endpoint reference

Pick an endpoint to see its parameters, try it with your own values and copy the code.

Case Converters

Text Tools

Developer Tools

Generators

Calculators

Case Converters

Uppercase

Turn every letter into a capital letter.

GET/api/v1/uppercase

Open the Uppercase tool on the website

Parameters

Name	Type	Description
textrequired	string	The text to convert.

Try it

Change the values and send a real request to the API from your browser.

text *

https://api.convert4me.com/api/v1/uppercase?text=the%20lord%20of%20the%20rings

Request

curl -G 'https://api.convert4me.com/api/v1/uppercase' \
  --data-urlencode 'text=the lord of the rings'

Response

Example response (200 OK) for the original example. Press “Send request” to see the live answer for your values.

{
  "ok": true,
  "tool": "uppercase",
  "action": "upper",
  "result": "THE LORD OF THE RINGS"
}