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Colly review

Free#34 of 49 in Web Scraping Tools

A free, self-hosted Go library for code-driven HTML and XML scraping.

5.0/10Editor score
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Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026

Colly is an open-source Go framework for developers building web scrapers, crawlers, and spiders. Its API makes network requests, processes returned HTML or XML, selects elements, and follows links. The library is intended for people who want to write and operate their own scraping programs, from simple jobs to larger crawlers; it is not a hosted scraping service. That makes it a fit for Go developers working with static page content, rather than teams looking for a point-and-click product.

Execution options are a notable strength: scraping can be synchronous, asynchronous, parallel, or distributed across proxies or multiple scraper instances. Developers can configure request delays and per-domain concurrency limits, while automatic cookie and session handling and response caching support recurring collection workflows. HTML and XML callbacks provide the extraction path, and robots.txt support is included. The documented storage backends include Redis and SQLite3, so Colly can connect to those systems when a crawler needs persistent storage. These are building blocks in a code library, not managed workflow controls.

Colly is free for commercial use, according to the official site, and is self-hosted. Its main trade-off is that implementation and operation remain with the developer: there is no hosted scraping service to take on those responsibilities. The official documentation describes HTML and XML response handling, not browser-based JavaScript rendering, so sites that require rendered client-side content may call for another approach. Choose Colly when Go, code-level control, and static HTML/XML are central requirements; consider a different tool if you need managed execution or JavaScript rendering.

Colly pros and cons

  • Where it wins
    • Runs scrapers synchronously, asynchronously, in parallel, or distributed.
    • Includes request delays, per-domain concurrency limits, sessions, and caching.
    • Supports HTML/XML callbacks, robots.txt, and Redis or SQLite3 storage.
  • Where it doesn't
    • Requires developers to build and run scraping programs themselves.
    • Does not provide browser-based JavaScript rendering.
    • Its documented storage integrations are Redis and SQLite3.

Colly fact sheet, pricing and score →

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