WeatherAPI.com vs Xweather Weather API

WeatherAPI.com

3 million calls for $7 a month, and 100,000 a month free with no card. Key only in the query string, and no security.txt.

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 REST credentials travel only in the query string, per-minute limits are unpublished, and the group terms bar commercial use of free plans and passing data to third parties unless a service description allows it.

WeatherAPI.com

1. Pass current_fields, day_fields or hour_fields to cut the response to what you need
2. Treat a 403 with error code 2007 as the monthly quota, not a bad key. There's no 429
3. Reuse the id from search.json (q=id:NNN) to avoid ambiguous city names
4. Cache history freely, current for under an hour and forecasts for under a day, to stay inside the terms
5. Use https://api.weatherapi.com/v1. The docs still show an http:// base URL

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