FMI Open Data API vs NASA POWER API

Two free Weather APIs compared on access, reliability and developer ratings, using data from our daily health checks.

The verdict

Choose FMI Open Data API if its data fits your use case better; on access and reliability it's level with NASA POWER API.
Choose NASA POWER API if you want faster responses.

	FMI Open Data API	NASA POWER API
What it does	Finnish weather, sea, climate and radar observations via open WFS.	Global solar and weather data for energy and agriculture.
Provider	Finnish Meteorological Institute	NASA POWER
API key	Not needed	Not needed
HTTPS	Yes	Yes
CORS (browser calls)	Yes	Yes
Status today	Online · 1444 ms	Online · 228 ms
Uptime (30 days)	Up	Up
Developer rating	Not rated yet	Not rated yet
Price	Free / free tier	Free / free tier

Finnish weather, sea, climate and radar observations via open WFS.

The majority of the Finnish Meteorological Institute's data is available as open data. The data is in a machine-readable, digital format.

Strengths

Global solar and weather data for energy and agriculture.

POWER Documentation Site

Strengths

Prototyping or a tutorial? Pick the one that needs no API key (both qualify).
Calling from a web page? You need CORS. Otherwise route requests through your own server or a serverless function.
Going to production? Favour HTTPS, a strong uptime record and a provider with clear rate limits and terms. Check each API's docs before you commit.
Still unsure? Both are free to try: send one request to each and compare the data you get back.

Neither needs an API key; you can call both straight away.