Best Open-Source SEO Tools 2026: 6 Options Compared
Best open-source SEO Tools compared: Lighthouse, Unlighthouse, SEOnaut, Yoast SEO and 2 more, with licenses, platforms and prices from official pages checked October 24, 2026.
•3 min read•SEO Tools
Quick comparison
| Tool | Price | Platforms | Best for | Tested |
|---|---|---|---|---|
| Lighthouse | Free (Free and open source; runs in Chrome DevTools or from the command line) | Chrome DevTools, CLI (Node.js) | Page-level technical checks | Docs only |
| Unlighthouse | Free (Free and open source) | CLI (Node.js) | Running Lighthouse across many pages | Docs only |
| SEOnaut | Free (Free and open source; self-host with Docker and MySQL. A hosted version exists at seonaut.org) | Web browser, Self-hosted | Site-wide technical audits | Docs only |
| Yoast SEO | Free (Free WordPress plugin with content analysis, schema, XML sitemaps, breadcrumbs and canonical URLs); paid from $118.8 per year (Premium; currency symbol not shown, prices exclude VAT) | WordPress plugin | WordPress on-page SEO | Docs only |
| SerpBear | Free (Free and open source; needs a third-party SERP scraping service or your own proxies to check Google positions) | Web browser, Self-hosted | Tracking keyword positions on your own server | Docs only |
| OpenSEO | Free (Free and open source; needs your own DataForSEO API key, which you pay for per use) | Web browser, Self-hosted | Developers who want an SEO toolkit for agents | Docs only |
Independent comparison. Paid placements are labelled separately; editorial links earn no affiliate commissions. Learn more.
Good fit if
- You want to audit pages for free (Lighthouse is the pick)
- You run a WordPress site (Yoast SEO is the pick)
- You want a self-hosted crawler (SEOnaut is the pick)
- You want to track rankings yourself (SerpBear is the pick)
Not ideal if
- You cannot host, patch and back up a server yourself and want a vendor to run it
Open-source SEO software is thinner than the open-source categories around it, because the valuable part of SEO data, such as rankings and link indexes, is expensive to collect and cannot be shipped in a repository. The tools here fall into two groups. The first works on your own pages: Lighthouse (Apache-2.0) audits a page for performance and SEO basics, Unlighthouse (MIT) is a Lighthouse-based site scanner, SEOnaut (MIT) crawls a site and reports issues from critical to low, and Yoast SEO (GPL-3.0) handles titles, schema and sitemaps inside WordPress. These need no outside data and cost nothing but your time. The second group tracks rankings and keywords, and here you pay a data provider: SerpBear (MIT) needs a SERP scraping service or your own proxies, and OpenSEO (MIT) needs a DataForSEO API key billed per use. So open source removes the licence fee, not the data cost. Pick the first group for technical audits and on-page work, and expect the second group to cost a small monthly amount in API charges. Check the activity of each repository before you rely on it, because small projects can stall. If you want one dashboard with rankings, links and keywords, the free hosted tools may cost you less time.
Lighthouse
Apache-2.0 auditor from Google, run in Chrome DevTools or as a Node CLI, with an seo category beside performance and accessibility. Page by page, not a site crawler.
Price: Free (Free and open source; runs in Chrome DevTools or from the command line) (Lighthouse pricing, checked 2026-10-24).
Platforms and license: Chrome DevTools, CLI (Node.js). Apache-2.0 (open source) (license source).
Project activity: 31k GitHub stars · latest release v13.6.0 (Oct 27, 2026) · last commit Oct 27, 2026
Best for: Page-level technical checks.
Worth knowing: Has an seo category beside performance, accessibility and best practices. CLI needs Node 22 or later.
Unlighthouse
MIT-licensed scanner that is Lighthouse-based; repository details were limited, so confirm what it covers before relying on it.
Price: Free (Free and open source) (Unlighthouse pricing, checked 2026-10-24).
Platforms and license: CLI (Node.js). MIT (open source) (license source).
Project activity: 4.9k GitHub stars · latest release v0.19.1 (Oct 3, 2026) · last commit Oct 27, 2026
Best for: Running Lighthouse across many pages.
SEOnaut
MIT-licensed crawler and auditor you self-host with Docker and MySQL; it reports issues as critical, high and low. A hosted version exists.
Price: Free (Free and open source; self-host with Docker and MySQL. A hosted version exists at seonaut.org) (SEOnaut pricing, checked 2026-10-24).
Platforms and license: Web browser, Self-hosted. MIT (open source) (license source).
Project activity: 844 GitHub stars · last commit Oct 8, 2026
Best for: Site-wide technical audits.
Yoast SEO
GPL-3.0 WordPress plugin with content analysis, schema, XML sitemaps and canonicals. Premium adds AI titles and redirects at 118.80 a year.
Price: Free (Free WordPress plugin with content analysis, schema, XML sitemaps, breadcrumbs and canonical URLs); paid from $118.8 per year (Premium; currency symbol not shown, prices exclude VAT) (Yoast SEO pricing, checked 2026-10-24).
Platforms and license: WordPress plugin. GPL-3.0 (open source) (license source).
Project activity: 2k GitHub stars · latest release 28.8 (Oct 27, 2026) · last commit Oct 27, 2026
Best for: WordPress on-page SEO.
Worth knowing: License is GPLv3 per the plugin readme.
SerpBear
MIT-licensed rank tracker with an API and email alerts. It needs a third-party SERP scraping service or your own proxies.
Price: Free (Free and open source; needs a third-party SERP scraping service or your own proxies to check Google positions) (SerpBear pricing, checked 2026-10-24).
Platforms and license: Web browser, Self-hosted. MIT (open source) (license source).
Project activity: 2.1k GitHub stars · latest release v3.1.0 (Mar 27, 2026) · last commit May 14, 2026
Best for: Tracking keyword positions on your own server.
Worth knowing: Scraper services are paid separately; optional Google Ads and Search Console integrations.
OpenSEO
MIT-licensed keyword research, rank tracking, backlink and audit tool that needs your own DataForSEO API key, charged per use.
Price: Free (Free and open source; needs your own DataForSEO API key, which you pay for per use) (OpenSEO pricing, checked 2026-10-24).
Platforms and license: Web browser, Self-hosted. MIT (open source) (license source).
Project activity: 25.3k GitHub stars · latest release v0.1.19 (Oct 26, 2026) · last commit Oct 26, 2026
Best for: Developers who want an SEO toolkit for agents.
Worth knowing: Covers keyword research, rank tracking, backlinks and site audits. Docker or Cloudflare deployment.
Which one to pick
- You want to audit pages for free: Lighthouse
- You run a WordPress site: Yoast SEO
- You want a self-hosted crawler: SEOnaut
- You want to track rankings yourself: SerpBear
Limits of this review
Docs-only for Lighthouse, Unlighthouse, SEOnaut, Yoast SEO, SerpBear, OpenSEO: we did not install or run them, so feature claims come from vendor pages. Vendor prices and free limits change; confirm on the linked pricing page before you commit.
Related guides
Sources
Kevin Fan
Kevin Fan is a SaaS founder. He runs Free Instead Of, which tracks free and open-source alternatives to paid software and checks each price and free-plan limit against the vendor's own pages.
Methodology
Based on official pricing, license and product pages checked 2026-10-24: Lighthouse, Unlighthouse, SEOnaut, Yoast SEO, SerpBear, OpenSEO. Prices, free limits and licenses are the figures shown on those pages on those dates. No tool on this page was installed or run. No accounts were created.