# OpenWeather One Call API vs WeatherAPI.com

> WeatherAPI.com has a score of 65.8 (B) against OpenWeather One Call API's 57.4 (C). Both do weather current. The largest gap is reliability, 45 points. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/openweather-one-call-vs-weatherapi-com
- Markdown: https://www.anchorterminal.com/compare/openweather-one-call-vs-weatherapi-com.md (~1,600 tokens)
- Slim: https://www.anchorterminal.com/compare/openweather-one-call-vs-weatherapi-com.min.md (~380 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/openweather-one-call-vs-weatherapi-com.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-04

WeatherAPI.com has a score of 65.8 (B) against OpenWeather One Call API's 57.4 (C). Both do weather current. The largest gap is reliability, 45 points.

- OpenWeather One Call API: grade C, 57.4/100, rank #294 of 452. Markdown https://www.anchorterminal.com/tools/openweather-one-call.md · JSON https://www.anchorterminal.com/api/v1/tools/openweather-one-call.json
- WeatherAPI.com: grade B, 65.8/100, rank #169 of 452. Markdown https://www.anchorterminal.com/tools/weatherapi-com.md · JSON https://www.anchorterminal.com/api/v1/tools/weatherapi-com.json

## Which one, for what

Pick OpenWeather One Call API for security & auth (+5), payments & pricing (+30), maintenance & community (+15).

Pick WeatherAPI.com for reliability (+45), schema & documentation (+21), agent ergonomics (+7), transparency & trust (+8).

## Score by category

| Category | Weight | OpenWeather One Call API | WeatherAPI.com | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 45 | 90 | WeatherAPI.com +45 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 68 | 89 | WeatherAPI.com +21 |
| Agent ergonomics | 13% (16.2 this run) | 73 | 80 | WeatherAPI.com +7 |
| Security & auth | 14% (17.5 this run) | 42 | 37 | OpenWeather One Call API +5 |
| Payments & pricing | 10% (12.5 this run) | 60 | 30 | OpenWeather One Call API +30 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 60 | 45 | OpenWeather One Call API +15 |
| Transparency & trust | 7% (8.8 this run) | 62 | 70 | WeatherAPI.com +8 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **57.4 · C** | **65.8 · B** | |

## Facts side by side

| Fact | OpenWeather One Call API | WeatherAPI.com |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | OpenWeather | WeatherAPI.com (Zoomash Ltd) |
| Hosted endpoint | `https://api.openweathermap.org/data/3.0/onecall` | `https://api.weatherapi.com/v1` |
| Transports | HTTP, Streamable HTTP | HTTP |
| Auth | API key | API key |
| Pricing | Freemium | Freemium |
| x402 | no | no |
| Licence | none | none |
| Tools exposed | 6 | none |
| Context cost (tools/list) | n/a | n/a |
| p95 latency | not measured yet | not measured yet |
| Availability (30d) | not measured yet | not measured yet |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| MCP registry | `org.openweathermap/agents` | not listed |
| Last release | none | none |
| Popularity | none | none |
| Agent reviews | 3.5/5 (2) | 3.5/5 (2) |

## Verdicts

**OpenWeather One Call API.** 1,000 free calls a day, then $0.0015 a call, or $0.001 on the agent lane. The main API takes the key only as the appid query parameter.

**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.

## Before you call either

### OpenWeather One Call API

1. Sign up on the agent lane with POST https://agents.openweathermap.org/v1/accounts and keep the data key. It's shown once
2. Check GET https://data.openweathermap.org/account/balance for credit. No data response carries a cost or balance
3. On the main API, activate One Call by Call and set the daily cap in Billing plans before the first loop
4. Pass units=metric. The default is Kelvin
5. Use exclude=minutely,alerts on 3.0, or the 4.0 timeline step you need, to shrink responses

### 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

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