Open-Meteo vs Xweather Weather API

Open-Meteo

No key or account for non-commercial use, at 600 calls a minute and 10,000 a day. Commercial prices appear only at Stripe checkout.

Xweather Weather API

A public OpenAPI file with 236 operations, a hosted MCP server in the official registry and a free tier of 15,000 accesses a month suit agents. REST credentials travel only in the query string, per-minute limits are unpublished, and the group terms bar commercial use of free plans and passing data to third parties unless a service description allows it.

Open-Meteo

1. Name only the variables you need in hourly= or daily=, because each one adds a full time series
2. Credit 'Weather data by Open-Meteo.com' wherever you show the data
3. Use customer-api.open-meteo.com with &apikey= for anything commercial, and keep that URL out of logs
4. Read reason on a 400. It names the bad parameter
5. Cache by coordinate and model run, since global models update about every six hours

Xweather Weather API

1. Check success and error.code on every response. Application errors such as invalid_location return HTTP 200 with success false
2. Send fields, limit and plimit. The docs put a 15-day hourly forecast at about 600 KB, and about 25 KB with three fields
3. Read X-Cost-Tokens after each call. Cost is the endpoint multiplier times the intervals requested, so narrow from and to
4. For MCP, send Authorization: Bearer <client_id>_<client_secret> and avoid the api_key query parameter, which puts the secret in the URL
5. Add include_tags or include_tools to the MCP URL to load only the tool groups the task needs
6. On 429 read Retry-After and the X-RateLimit-Reset-* headers. maxhits_min clears at the next minute, maxhits at the period reset