A weather app, a recipe finder with real calories, a currency converter… Almost every app you can imagine uses data that another website already gives away for free through an API.
The place to find them is public-apis, the biggest list of free APIs on GitHub. And to connect them without knowing how to code there’s Claude Code: you give it the docs, tell it what you want and it builds it.
From the list to a working app
Pick an API
On public-apis, by category: weather, food, currencies, books…
Open its documentation
The link in the list itself takes you there.
Hand it to Claude Code
With the exact sentence below.
Claude writes and tests the code
If it needs a key, it reads it from your .env file.
You have the data
And from there, to a website, a bot or a spreadsheet.
What public-apis is
- Repo: public-apis/public-apis, “A collective list of free APIs”.
- Almost 500,000 stars on GitHub (497,159 as of November 8, 2026), one of the most popular repos on the whole platform. MIT license.
- Over 1,000 APIs that are free or have a free tier, in more than 50 categories: weather, food, finance, games, books, transport, health…
Each API takes up one row of a table with five columns. These are the ones to look at:
| Column | What it tells you | What to look for as a beginner |
|---|---|---|
| Auth | Whether it needs a key: No, apiKey or OAuth | No |
| HTTPS | Whether the connection is encrypted | Yes |
| CORS | Whether it can be called directly from a website | Yes (or Unknown, and you test) |
Note
“Free” doesn’t always mean “unlimited”. Many have a free tier with a cap on requests per day or per month. For practice and small projects it’s more than enough. If you’re building something serious, read their terms first.
10 no-key APIs to start with today
We called them one by one on November 8, 2026 and all of them responded with no key and no sign-up:
| API | What it gives you | Quick idea |
|---|---|---|
| Open-Meteo | Current weather and forecast for anywhere | Your own weather app |
| PokéAPI | Every bit of Pokémon data | The best one to practice with |
| Open Library | Books, authors and covers | Book finder |
| Nager.Date | Public holidays for every country | Long-weekend calendar |
| Frankfurter | Currency exchange rates | Currency converter |
| Wikipedia REST API | Article summaries | “Explain X in 3 lines” |
| Open Food Facts | Calories and ingredients by barcode | Recipes with real calories |
| Dog CEO | Dog photos by breed | A widget to brighten your day |
| JokeAPI | Jokes (in several languages) | A joke bot |
| Sunrise-Sunset | Sunrise and sunset times | Golden-hour photo alerts |
Two that almost made it, but not quite:
- TheMealDB (recipes): works with a public test key, the number
1, which is in its own documentation. Fine for practice; to publish an app they ask for your own key. - CoinGecko (crypto prices): now requires a free Demo key. It’s free, but you have to sign up.
The exact sentence for Claude Code
- Open the API’s documentation (the link in the list).
- Open Claude Code in a new folder for the project.
- Paste the sentence, changing the link and what you want:
Read this documentation: [LINK TO THE API DOCUMENTATION]. Use it to make me a function that [WHAT YOU WANT, for example: gives me the current temperature in Chicago]. If it needs a key, read it from a .env file and don't write it in the code.- When it’s done, ask it to test it:
Run it and show me the result. If it fails, tell me why and fix it.Tip
A first example to try. Go with Open-Meteo: “Read this documentation: https://open-meteo.com/en/docs. Use it to make me a function that gives me the current temperature and tomorrow’s in Chicago.” It needs no key, so it works first time.
Once you have the data, the next step is to ask for whatever you want to build on top of it: “make a simple web page that shows it”, “send it to me on Telegram every morning”, “save it in a spreadsheet”.
App ideas to practice with
- Recipes with real calories: TheMealDB for the recipe + Open Food Facts for the nutrition values.
- Travel dashboard: weather (Open-Meteo) + the country’s public holidays (Nager.Date) + exchange rate (Frankfurter).
- Live crypto prices: CoinGecko with its free Demo key.
- Today’s headlines: you need a news API with a key (NewsAPI, GNews…). A good exercise for your first .env.
If the API needs a key: the .env file
An API key is like the password to your account on that API. If someone copies it, they use up your quota (or your money). Three rules:
- Store it in a
.envfile in the project folder:
API_NAME_KEY=paste_your_key_here
- Add
.envto.gitignoreso it never gets pushed to GitHub:
echo ".env" >> .gitignore
- Never paste it into the chat or the code. Tell Claude Code “the key is in .env as API_NAME_KEY” and to read it from there.
If one has already leaked, revoke it on the API’s website right away and generate a new one: deleting it from the code isn’t enough, because it stays in the Git history.
What it doesn’t do
- public-apis isn’t an API. It’s a list: every API has its own rules, limits and documentation.
- Not everything is still alive. It’s maintained by the community and some APIs may have shut down or changed (it happened to us with REST Countries, which has changed version). If one fails, try another in the same category.
- Claude Code doesn’t guess. If the docs are bad or the API is down, the code will fail. Ask it to tell you why.
Is it worth it?
Yes, especially if you want to learn to build things without knowing how to code. With a no-key API and one sentence, in ten minutes you have real data on your screen. And it’s the best way to understand what an API is: use one.