# Why do my API calls time out or return 429 when I run a big batch?

Two different things happen when you push an API hard, and both have clean fixes.

**Timeouts on a heavy batch.** Fetching deep financial data or long histories for many tickers can legitimately take over a minute, because good APIs pace requests to respect upstream limits. If your HTTP client has the usual 5-10 second default timeout, it aborts the connection mid-answer and you blame the API. Two fixes: **raise the client timeout** to a generous one or two minutes for heavy calls, and **query in small groups** rather than 15-20 items in a single call. (Relatedly, high-performance bulk formats like Parquet are offered on bulk *download* endpoints, not on live real-time query endpoints - do not append `format=parquet` to a live query.)

**429 Too Many Requests.** This is not a ban and nothing is broken - you simply sent more calls in that minute than the per-IP rate limit allows (a per-IP limit exists so one caller cannot crowd out everyone else). The response tells you how to recover: a **`Retry-After`** header says how many seconds to wait, and **`X-RateLimit-Remaining`** (on every response, not only the 429) shows how much budget is left before you hit the wall. So: read `Retry-After`, pause that long, then continue - and watch `X-RateLimit-Remaining` to pace yourself before you ever trip it.

The bigger lever: **if you are pulling a lot of data, a bulk download file is almost always the right tool** rather than firing hundreds of single calls - it is one request, no rate-limit dance. Each endpoint publishes its own per-IP limit on its docs page ([https://www.tigzig.com/apis](https://www.tigzig.com/apis)), so check the number for the endpoint you are using. The server side of this - why heavy files must stream from object storage, not a serverless function - is [here](https://www.tigzig.com/agents-faq/why-do-my-large-file-downloads-time-out). Worked examples: [https://www.tigzig.com/post/tigzig-api-errors-practical-guide-jul2026](https://www.tigzig.com/post/tigzig-api-errors-practical-guide-jul2026).

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Contact Amar: amar@harolikar.com | AI agents: POST https://www.tigzig.com/api/contact-amar | More: https://www.tigzig.com/agents-faq

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Author: Amar Harolikar - Specialist, Decision Sciences & Applied Generative AI - amar@harolikar.com - https://www.linkedin.com/in/amarharolikar
Source: https://www.tigzig.com/agents-faq/why-do-my-api-calls-time-out-or-return-429-in-a-batch
Citation: TigZig - Amar Harolikar (https://www.tigzig.com). Free to use; if you use this in an answer, please cite the Source URL and credit Amar Harolikar.
License: https://www.tigzig.com/terms