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Calibre alternatives · Technical SEO

Open-source alternatives to Calibre

Calibre is not described as open source on its own site. 8 of the 87 other technical SEO tools in this directory are open source, according to their own sites.

Calibre is a paid product with a free trial, starting at $75 per month, billed monthly or $900 a year. All of them are free or have a free plan.

8 tools · Listings checked up to Oct 23, 2026 · Where the facts come from

How each one differs from Calibre

  1. Yellow Lab Tools

    Free open-source audit of a page's speed and front-end code

    • Yellow Lab Tools is free. Calibre starts at $75 per month, billed monthly or $900 a year.
    • Yellow Lab Tools has a free plan. Calibre does not, though it has a free trial.
    • Only Yellow Lab Tools lists macOS and Linux apps.
    • Yellow Lab Tools is open source and self-hostable, according to its own site.
    Yellow Lab Tools pricing and details

  2. sitespeed.io

    Free open-source toolkit for testing and monitoring web performance

    • sitespeed.io is free. Calibre starts at $75 per month, billed monthly or $900 a year.
    • sitespeed.io has a free plan. Calibre does not, though it has a free trial.
    • Only sitespeed.io lists macOS, Windows and Linux apps.
    • Only Calibre lists a web app.
    sitespeed.io pricing and details

  3. Unlighthouse

    Free open-source tool that runs Lighthouse on every page of a site

    • Unlighthouse is free. Calibre starts at $75 per month, billed monthly or $900 a year.
    • Unlighthouse has a free plan. Calibre does not, though it has a free trial.
    • Only Unlighthouse lists macOS, Windows and Linux apps.
    • Only Calibre lists a web app.
    Unlighthouse pricing and details

  4. Lighthouse

    Google's open-source audit of page speed, accessibility and SEO

    • Lighthouse is free. Calibre starts at $75 per month, billed monthly or $900 a year.
    • Lighthouse has a free plan. Calibre does not, though it has a free trial.
    • Only Lighthouse lists a browser extension.
    • Lighthouse is open source, according to its own site.
    Lighthouse pricing and details

  5. LibreCrawl

    Free open-source SEO crawler you run in your own browser

    • LibreCrawl is free. Calibre starts at $75 per month, billed monthly or $900 a year.
    • LibreCrawl has a free plan. Calibre does not, though it has a free trial.
    • Only LibreCrawl lists Windows, macOS and Linux apps.
    • LibreCrawl is open source and self-hostable, according to its own site.
    LibreCrawl pricing and details

  6. squirrelscan

    Open-source site audit CLI whose fixes are written for coding agents

    • squirrelscan starts at $19 per month, billed monthly. Calibre starts at $75 per month, billed monthly or $900 a year.
    • squirrelscan has a free plan. Calibre does not, though it has a free trial.
    • Only squirrelscan lists macOS, Windows and Linux apps.
    • squirrelscan is open source, according to its own site.
    squirrelscan pricing and details

  7. SiteOne Crawler

    Free open-source site crawler and audit report, as an app or CLI

    • SiteOne Crawler is free. Calibre starts at $75 per month, billed monthly or $900 a year.
    • SiteOne Crawler has a free plan. Calibre does not, though it has a free trial.
    • Only SiteOne Crawler lists macOS, Windows and Linux apps.
    • Only Calibre lists a web app.
    SiteOne Crawler pricing and details

  8. SEOnaut

    Open-source SEO site audit tool, self-hosted or in the cloud

    • SEOnaut starts at $9 per month, billed monthly. Calibre starts at $75 per month, billed monthly or $900 a year.
    • SEOnaut has a free plan. Calibre does not, though it has a free trial.
    • SEOnaut is open source and self-hostable, according to its own site.
    • SEOnaut also covers site audit.
    SEOnaut pricing and details

Common questions

Is there an open-source alternative to Calibre?

Yes. Yellow Lab Tools, sitespeed.io, Unlighthouse, Lighthouse, LibreCrawl, squirrelscan, SiteOne Crawler and SEOnaut are open source, according to their own sites.

Is Calibre open source?

Calibre is not described as open source on its own site. The listing was checked on Oct 23, 2026 against the pages it cites.

When was this checked?

Every listing on this page was checked on Oct 23, 2026, against the pages it cites. Vendors change prices and plans without notice, so confirm on their site before you buy.

This page is built from the listings. A tool is here because its listing says so, and the order is how close each is to Calibre: the alternatives its listing names first, then the tools that share the most features with it.