Stormglass API vs The Weather Company Data APIs

Stormglass API

A read-only weather and marine API with about 70 hourly parameters, per-source values from named national models, tide data and ERA5 history from 2014. No OpenAPI file, status page, SDK or security page was found, the free plan allows 10 requests a day, and the docs and FAQ disagree on the status code for a spent quota.

The Weather Company Data APIs

A wide weather data API with 168 API references built from OpenAPI documents, global 4 km current conditions, hourly history from June 2015 and a status page with component history. Keys come only through a sales-reviewed trial or contract, travel only in the URL, and the terms that govern the API are not published.

Stormglass API

1. Send the key as Authorization: KEY with no Bearer prefix. A missing or wrong key returns 403 with {"errors":{"key":"API key is invalid"}}
2. Always pass source=sg or a short source list on /weather/point. The default is every source, which multiplies the size of each hourly record
3. Treat 402 as a spent daily quota, not a billing failure, and stop until the next day. Read meta.requestCount against meta.dailyQuota on each response
4. Use /historical/point for past dates, at most 10 days a call and nothing newer than about 7 days. /weather/point looks back 14 days only
5. Send and read all times in UTC. Tide sea levels are relative to the chosen datum (MSL by default) and are not water depth

The Weather Company Data APIs

1. Send units, language and format=json with a location on every v3 call, plus Accept-Encoding: gzip, which the usage guide marks as required.
2. Keep the key out of logs and client-side code, because it travels in the query string as apiKey.
3. Treat a 401 as either a bad key, an endpoint outside the key's package or an exceeded limit, and treat a 204 as no data for the query.
4. Each forecast duration (3day to 15day) is a separate entitlement. Request only durations the contract covers.
5. Use /v3/aggcommon to combine up to 10 products in one request. Each product and each location still counts as one call.