You can start a project with a free API, but “free” rarely means unlimited, anonymous, or suitable for every commercial use. The seven services below cover weather, NASA data, public repositories, books, countries, exchange rates and website screenshots. The first six are documented data services; ScreenshotNeo is a practical API when your project needs rendered web pages. Check each provider’s current documentation before shipping because quotas, versions and lifecycle notices can change.
Quick comparison
| API | Best for | Authentication | Documented limits or terms |
|---|---|---|---|
| Open-Meteo | Forecasts and historical weather | No key or signup for the hosted non-commercial tier | 600 calls/minute, 5,000/hour and 10,000/day on the free tier; attribution required for the data; hosted free access is non-commercial |
| NASA Open APIs | NASA imagery and scientific data | Explore without authentication; a key is recommended for intensive use | 1,000 requests/hour per API key; DEMO_KEY is 30/hour and 50/day per IP |
| GitHub REST API | Public repositories and activity | Unauthenticated public requests or an authenticated credential | 60 unauthenticated requests/hour; secondary limits also apply |
| Open Library | Human-facing book search and lookup | Public HTTP API | One request/second by default, three/second when identified; bulk backends are discouraged |
| REST Countries | Country and region reference data | Public HTTP API | Version 5 is the documented stable version; 20 requests per 10 seconds, with HTTP 429 above the ceiling |
| Frankfurter | Daily and historical exchange rates | No API key | No daily or monthly quota, but abuse prevention still rate-limits requests; not a live-trading feed |
| ScreenshotNeo | Website screenshots and PDFs | API key | Free 1,000 shots/month; paid plans start at $5 for 3,000 shots |
1. Open-Meteo for weather
Open-Meteo returns JSON forecasts and historical weather through HTTP GET requests. Its overview says a key or signup is not required for non-commercial use. It also offers related air-quality, marine, geocoding, elevation and flood APIs.
Limits and licensing
The published free limits are 600 calls per minute, 5,000 per hour and 10,000 per day. The hosted free tier is non-commercial. Separately, the service says its data are available under CC BY 4.0, which requires attribution. Do not treat the data license as permission to use the hosted free service commercially; verify the commercial plan and current terms first. Open-Meteo also provides its API data without warranty, so forecasts should not be treated as guaranteed outcomes.
Good project fit
Use it for a personal dashboard, prototype or non-commercial application that can cache results and display attribution. For a commercial product, confirm the current plan, limits and attribution wording before launch.
The Tool Desk
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2. NASA Open APIs for public NASA data
NASA’s API portal catalogs developer-facing access to NASA data and imagery. You can explore without authentication, but NASA recommends registering for a key when making intensive requests.
Keys and quotas
A registered key has a documented default limit of 1,000 requests per hour across services at api.nasa.gov. The DEMO_KEY is intended for exploration and is limited to 30 requests per hour and 50 per day per IP. Responses include rate-limit headers; use them to decide when to slow down instead of retrying blindly.
Check lifecycle notices
Do not copy an old tutorial without checking the portal. NASA says the legacy APOD API is scheduled for archive on December 1, 2026. Its Earth API has been archived and replaced by Earthdata GIBS, and the Mars Rover API has also been archived. Choose the current endpoint for the particular NASA dataset you need.
3. GitHub REST API for repository data
GitHub’s REST API is useful for public repository metadata, issues, releases and activity. Unauthenticated requests can fetch public data, but the primary limit is 60 requests per hour.
Authentication and secondary limits
Authenticated requests generally receive higher primary limits, but the exact allowance depends on the authentication method and endpoint. GitHub also applies secondary limits covering concurrency and request activity; these can change without notice. Read rate-limit and reset headers, keep secrets out of browser code, and use exponential backoff when a request is refused. A tight retry loop can make a temporary restriction worse.
Rank #2
When it fits
It is a reasonable choice for a dashboard or integration tied to GitHub activity. Read the endpoint-specific documentation before assuming that one resource’s quota or fields apply to another.
4. Open Library for book discovery
Open Library exposes catalog and author information in JSON, YAML and RDF/XML. It is designed for public-good, human-centered lookup and discovery.
Expected traffic pattern
The guidance documents a default rate of one request per second, or three requests per second for identified applications. Identify your client with a User-Agent and contact email, cache responses, and avoid treating the API as a high-traffic commercial backend. For bulk access, Open Library recommends monthly data dumps rather than hammering live endpoints.
Best use
Use it behind a search box, reading list or small recommendation feature. Queue and cache requests if several users can trigger the same lookup.
5. REST Countries for reference data
REST Countries supplies country information for selectors, profile pages and regional reference features. The current documentation identifies version 5 as the first long-term-stable version and marks versions 1 through 4 as deprecated.
Throughput rule
The documented ceiling is 20 requests per 10 seconds across traffic. Sustained traffic above that receives HTTP 429 responses. Use the current version documented by the service instead of copying older v3 examples, and cache country records that change infrequently.
6. Frankfurter for exchange rates
Frankfurter provides current daily rates, historical rates for a date and time series without an API key. It tracks daily rates from central banks and other official sources and includes historical data back to 1948.
Recommended Free Tools
What “no quota” means
Its FAQ says there are no daily or monthly quotas, but requests are still rate-limited to prevent abuse. Rates are subject to the terms of their individual data providers.
Use cases and boundary
Frankfurter can suit billing, e-commerce, tax reporting, accounting and research that can work with daily rates. It is not built for live trading or exotic currencies with highly volatile intraday movements. Store the date and source of every rate used in an auditable transaction.
7. ScreenshotNeo for rendered web pages
ScreenshotNeo is a website screenshot API and MCP server. A GET request returns a PNG, JPEG, WebP or PDF. Before capture, it can accept cookie or consent banners and remove more than 60 known consent platforms, newsletter popups and chat widgets; each step can be disabled. Bot checks, CAPTCHAs, blank pages, timeouts, failed loads and cache hits are not billed, and response headers report the page verdict and whether the request was billed.
One-call example
See the full option list and parameter reference in the ScreenshotNeo documentation.
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- Full-page capture with lazy images loaded, or one element selected by CSS.
- Dark mode, 12 device presets, arbitrary viewports and retina scale.
- PDF paper size, margins, landscape mode and page ranges.
- HTML/CSS rendering, custom CSS and JavaScript, pre-capture clicks, hidden selectors and waits for a selector, delay or network idle.
- Ad, tracker, request and resource-type blocking; custom headers, cookies, user agent and Authorization.
- Timezone and geolocation, transparent backgrounds, resizing and a chosen cache TTL.
- Signed public image links, asynchronous jobs with signed webhooks, bulk capture of up to 100 URLs per call, a usage API and an OpenAPI specification.
Its parameter names are compatible with those used by other screenshot APIs, which can simplify migration. Pricing is Free: 1,000 shots/month with no card; Starter: $5 for 3,000; Growth: $15 for 15,000; Pro: $39 for 60,000; Scale: $99 for 250,000; Business: $249 for 1,000,000. Yearly billing gives two months free, and every feature is on every plan.
Or skip the browser setup
Cookie banners, popups and chat widgets are removed before the shot. Bot checks, blank pages and failed loads are never billed. An MCP server lets Claude, Cursor and other MCP clients call take_screenshot, get_page_info and capture_pdf. You get 1,000 screenshots a month free with no card, and paid plans start at $5 for 3,000.
import requests
r = requests.get("https://api.screenshotneo.com/v1/shot", params={"access_key": "YOUR_API_KEY", "url": "https://stripe.com"}, timeout=90)
open("shot.webp", "wb").write(r.content)Create a free ScreenshotNeo account to get an API key.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How to choose a free API responsibly
Match the data to the job
Start with the service family: weather, NASA data, repository activity, books, country references, exchange rates or rendered pages. A technically free endpoint is still a poor choice if its freshness or intended audience does not match your product.
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Estimate requests per user, refresh interval, retries and background jobs. Compare that total with documented per-minute, hourly, daily or burst limits. Cache stable data and batch work where the provider supports it.
Separate access terms from data rights
An endpoint’s authentication policy does not automatically grant commercial rights to returned data. Open-Meteo’s hosted free access is the clearest example: non-commercial service access and CC BY data licensing are separate questions. Check attribution, redistribution and acceptable-use terms for every provider.
Best Value
Plan for change
Pin the API version where possible, monitor response headers, log errors and subscribe to provider announcements. NASA’s archived APIs and REST Countries’ deprecated versions show why an old code sample is not a maintenance plan.
Troubleshooting common failures
- HTTP 429: you exceeded a quota or burst ceiling. Stop retries, honor reset information, add backoff and cache responses.
- Authentication errors: confirm whether the service needs a key, whether the key is active and whether it is being sent in the documented location. Never expose private keys in client-side JavaScript.
- Empty or stale data: verify the endpoint version, requested date or geography, and whether the provider publishes daily rather than intraday data.
- Sudden break after an upgrade: check lifecycle notices and deprecated-version warnings before changing application logic.
- Slow pages: move calls to a server, batch or cache them, and avoid making one API request per visible UI element.
Frequently Asked Questions
Can I promise users that a free API will always remain free?
No. Treat pricing, quotas and lifecycle notices as changeable terms and design an exit or replacement path.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Should API calls run in the browser?
Only when the provider explicitly allows public access and no secret is involved. Put keyed requests on your server and enforce your own rate limits.
Which option is suitable for intraday currency trading?
None of the services listed here is presented as a live-trading feed; Frankfurter specifically says it is not designed for that use.
The Bottom Line
Choose by data fit first, then verify quota, authentication, licensing and lifecycle status. Free access is a starting point—not a guarantee of unlimited or commercial use.
Quick Recap
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