AltF Developers
Free JSON API quickstart (no API key)
Every AltFTool endpoint is a plain HTTPS GET that returns JSON. There is no key, header or sign-up: copy a URL, call it with cURL, fetch, requests or PHP, and parse the JSON. Cache the response for as long as its Cache-Control header allows and, if you ever get a 429, wait for the Retry-After seconds.
- No API key
- Free, no sign-up
- Real responses, no mock data
- Code in 5 languages
API explorer
Pick an endpoint, set the parameters and send a real request. No key needed.
Search-demand signals for tool ideas: name, query, category, estimated search volume, opportunity score, competition and momentum.
Matches name, query, summary and category. Trimmed, first 100 characters.
Exact category match. Empty means all.
Exact momentum match. Empty means all.
Unknown values fall back to opportunity.
GEThttps://www.altftool.com/api/signalsCode for this request
curl -sS -H "Accept: application/json" 'https://www.altftool.com/api/signals'
Your first request
Run this in a terminal: curl -H "Accept: application/json" "https://www.altftool.com/api/signals?sort=volume". You get back an object with dataAsOf, count and results. Every other endpoint works the same way, and the explorer above writes the code for each one.
Which endpoint to start with
- Need data in another site's browser? Use the open-data endpoints or /api/oembed: they allow any origin.
- Need ranked tool ideas? Use /api/signals from your server.
- Checking whether the site is up before a batch job? Use /api/health, at most once a minute.
Good client habits
- Send Accept: application/json and a descriptive User-Agent so problems can be traced.
- Cache responses: signals for an hour, open data for a day.
- Treat unknown fields as optional and never depend on the order of results unless you set sort.
- Back off on 429 and on 5xx; never retry in a tight loop.
Limits, CORS and caching
| Endpoint | Returns | Browser CORS | Rate limit | Cache |
|---|---|---|---|---|
| GET /api/signals | Signals catalogue | Same origin only | 60 requests per minute per client | CDN 1 hour, then stale for up to 24 hours |
| GET /api/open-data/exam-photo-specs | Exam photo and signature specs | Any origin (Access-Control-Allow-Origin: *) | No per-client limit; served from cache | Browser and CDN 24 hours, stale for up to 7 days |
| GET /api/open-data/transform-converters | Format converter index | Any origin (Access-Control-Allow-Origin: *) | No per-client limit; served from cache | Browser and CDN 24 hours, stale for up to 7 days |
| GET /api/oembed | oEmbed provider | Any origin (Access-Control-Allow-Origin: *) | No per-client limit; cached at the CDN | CDN 1 hour, then stale for up to 24 hours; cache_age 86400 |
| GET /api/health | Site health | Same origin only | 30 requests per minute per client | CDN 60 seconds, then stale for up to 2 minutes |
Read from each route's source code on 2026-11-01.
Free JSON API quickstart (no API key): questions and answers
Is this a good free API for testing and learning?
Yes. It needs no key, returns small, real JSON, and has a CORS-open option (the open-data endpoints), so it works for fetch tutorials, Postman collections and front-end practice.
Do I need to sign up?
No. There is no account system for the API at all.
Which languages are supported?
Any language that can make an HTTPS GET request. The explorer generates cURL, JavaScript (browser fetch), Node.js, Python and PHP code.
More developer reference
- Signals API referenceGET /api/signals returns search-demand signals for tool ideas: query, category, search volume estimate, opportunity score and momentum. Parameters, fields and examples.
- Open data API referenceTwo free open datasets with CORS enabled: Indian exam photo and signature specs, and the AltFTool file converter index. Fields, attribution rules and code.
- oEmbed provider referenceAltFTool's oEmbed endpoint turns a pasted tool URL into a live widget in WordPress, Ghost and any oEmbed consumer. Parameters, response, errors and a live tester.
- Embed free tool widgets on your siteEmbed free AltFTool calculators, converters and generators on your site with one iframe, a responsive wrapper or a WordPress block. Builder, preview and rules.
- Feeds, sitemaps and llms.txtEvery machine-readable AltFTool file: RSS feed, XML sitemap, Google News sitemap, llms.txt, llms-full.txt, ai.txt and robots.txt, with refresh times and uses.
- Rate limits, 429s and cachingAltFTool API rate limits and cache headers per endpoint, what a 429 response contains, and copyable retry-with-backoff code that honours Retry-After.
Free developer tools
Requests and APIs
JSON and data
Built something with it? Get it seen
Credit AltFTool with a normal link to the page you used, then list your own project where developers look. Our backlinks directory sorts free places to submit a site by type and authority.