Open-Source SEO Tools: 2026's Best Semrush Alternatives

There is no single open-source tool that replaces Semrush one to one, but you can cover most of its jobs with a small open-source stack: OpenSEO or SerpBear for keywords and rankings, advertools or Scrapy for crawling, Lighthouse for performance, GoAccess for log files and Matomo or Plausible for analytics. What open source does not give you is the data behind Semrush: a keyword database with search volumes and a web-wide backlink index. For that you either pay a data API or rely on free first-party sources such as Google Search Console.

Below you find only tools with a public repository and a license you can check yourself, grouped by the Semrush feature they replace.

What counts as open source (and what does not)

"Free" and "open source" are not the same. Open source means the code is published under a license that meets the Open Source Definition, which among other things allows free redistribution and modification. Three categories often get mixed up in "Semrush alternative" lists:

• Open source: code and license are public, for example MIT, Apache-2.0, BSD or GPL. You can self-host and change it.
• Source-available: the code is visible, but the license restricts use. n8n, the popular workflow tool, uses its own Sustainable Use License and describes itself as "fair-code", not open source.
• Freeware: free to use, code closed. The free version of Screaming Frog SEO Spider belongs here. It is a good tool, but not open source.

The distinction matters if you want to self-host, modify the tool or depend on it long term.

Open-source Semrush alternatives by use case

Semrush job	Open-source tool	License	Note
Keyword research, rank tracking, backlinks, site audit	OpenSEO	MIT	Self-hostable all-in-one interface; needs a paid SEO data API key
Rank tracking	SerpBear	MIT	Uses a scraping service or your own proxies; Search Console integration
Site crawl and technical audit	advertools	MIT	Python: crawler, sitemaps, robots.txt, log files
Custom or large crawls	Scrapy, Apache Nutch, Apache StormCrawler	BSD-3 / Apache-2.0	Frameworks, need development work
Broken links	LinkChecker	GPL-2.0	Command line, recursive link check
Performance and Core Web Vitals	Lighthouse, Unlighthouse	Apache-2.0 / MIT	Unlighthouse runs Lighthouse across a whole site
Log file analysis	GoAccess, AWStats	MIT / GPL-3.0	See which bots crawl which URLs
Traffic analytics	Matomo, Plausible	GPL-3.0 / AGPL-3.0	Self-hosted web analytics
Dashboards and scheduling	Metabase, Apache Airflow, OpenSearch	AGPL (open edition) / Apache-2.0	Reporting, scheduled jobs, search over crawl and log data

Licenses as stated in each repository at the time of writing. Check the repository before you build on a tool, because licenses and maintenance status change.

OpenSEO: the closest thing to an open-source Semrush

OpenSEO describes itself as an open-source alternative to Semrush and Ahrefs. According to its README, it covers keyword research, rank tracking, competitor insights, backlinks, site audits and AI visibility, and it exposes an MCP server so AI agents can use the data. You can self-host it with Docker or on Cloudflare. The important detail: the SEO data itself comes from a paid third-party data API, which you pay per request. The software is open, the data is not.

SerpBear: self-hosted rank tracking

SerpBear tracks keyword positions in Google for unlimited domains and keywords and sends change notifications by email. It checks rankings through third-party scraping services or proxies you provide, and it can show search volumes if you connect a Google Ads account. Serposcope, which older lists still recommend, has been archived on GitHub since January 2024 and is no longer maintained.

Crawling and technical audits

For most sites, advertools is the fastest start: one Python function crawls a site and writes every URL with title, meta description, headings, status code and links to a file you can analyze in pandas. Scrapy is the framework advertools builds on and suits custom extraction. Apache Nutch and StormCrawler are built for very large, distributed crawls; they are overkill for a single company website.

Log files: what bots actually do

Server logs are the only reliable way to see how often Googlebot, Bingbot or AI crawlers such as GPTBot request your pages. GoAccess turns a standard access log into an HTML report in seconds. Filter the log by user agent first if you want a bot-only view. If you want to check whether AI crawlers can reach your site at all, the AI crawler check tests your robots.txt rules per bot.

First steps: three commands

You can test the core of an open-source stack in an afternoon. These examples assume Python and Node.js are installed and that you have access to your server logs.

# 1. Crawl your site with advertools (Python)
pip install advertools
python -c "import advertools as adv; adv.crawl('https://www.example.com', 'crawl.jsonl', follow_links=True)"

# 2. Run Lighthouse across all pages with Unlighthouse
npx unlighthouse --site https://www.example.com

# 3. Build a log report with GoAccess
goaccess access.log --log-format=COMBINED -o report.html

Load crawl.jsonl into pandas or a spreadsheet and filter for status codes, missing titles and duplicate descriptions. That already replaces the basic part of a Semrush site audit.

What open-source SEO tools cannot do

This is where most "free Semrush alternative" lists stop being honest. Semrush's value is mostly its data, not its interface, and that data is expensive to collect:

• Keyword database: no open-source project ships search volumes, keyword difficulty or historical SERPs. OpenSEO and similar tools fetch them from paid APIs; SerpBear uses Google Ads data for volumes.
• Backlink index: a web-wide link index requires crawling a large part of the web continuously. No open-source SEO tool provides one out of the box.
• Competitor traffic estimates: estimated traffic for other domains is modeled from proprietary data and has no open-source equivalent.
• Maintenance: self-hosting means updates, backups and fixes are your job. Rank tracking in particular breaks when search result pages change.

The free first-party alternatives cover part of the gap for your own site: Google Search Console shows real queries, impressions and positions; Bing Webmaster Tools does the same for Bing; Google Keyword Planner gives volume ranges with a Google Ads account. Ahrefs Webmaster Tools is free for verified site owners and shows backlinks to your own site. Semrush itself also offers a limited free account.

Which stack fits which team

• Solo marketer without a developer: Search Console, Unlighthouse and the free Screaming Frog version (freeware) for audits. Add OpenSEO if you need keyword data and are fine paying per request.
• In-house team with technical support: advertools for scheduled crawls, GoAccess for logs, Matomo or Plausible for analytics, Metabase as the reporting layer.
• Agency with many clients: SerpBear for rank tracking across client domains, OpenSEO for research, Airflow to schedule crawls and exports. Budget for the data API and for maintenance time.

The gap no SEO tool covers: AI answers

Semrush and its open-source alternatives were built for classic search results. More and more buyer questions are answered directly in ChatGPT, Perplexity, Gemini or Google AI Overviews, and rankings do not tell you whether those answers name your brand or cite your pages. OpenSEO lists AI visibility as a workflow, which shows where the category is heading.

If you want to know where you stand today, the free GEO check tests how well a page is prepared for AI answers, and the AI visibility checker tracks which AI systems mention your brand for your customers' questions. For a comparison of dedicated tools, see our GEO tool comparison.

FAQ

Is there an open-source alternative to Semrush?

Yes, with limits. OpenSEO (MIT license) is the closest all-in-one alternative, covering keyword research, rank tracking, backlinks and site audits, but it needs a paid SEO data API for the data. Specialized tools such as SerpBear, advertools and Lighthouse cover individual jobs.

Is there a free alternative to Semrush?

For your own site, Google Search Console, Bing Webmaster Tools and Ahrefs Webmaster Tools are free and use real data. Open-source tools are free to use, but keyword and backlink data for other domains usually costs money through an API.

Can I use Ahrefs for free?

Partly. Ahrefs Webmaster Tools is free for sites you can verify and includes site audit and backlink data for those sites. Research on other domains requires a paid plan.

Is Screaming Frog open source?

No. Screaming Frog SEO Spider has a free version with a URL limit, but the code is closed. It is freeware, not open source.

Is n8n open source?

Not in the strict sense. n8n is source-available under its Sustainable Use License and calls itself "fair-code". Apache Airflow (Apache-2.0) is an open-source option for scheduling SEO jobs.

Do open-source SEO tools include keyword search volumes?

No open-source project ships its own keyword database. Tools like OpenSEO or SerpBear fetch volumes from paid APIs or from a connected Google Ads account.

To place this measure in the wider context of technical access, content and measurement, read our generative engine optimization guide.