# Yellow Lab Tools review (2026): is it any good? > Free open-source audit of a page's speed and front-end code Checked Oct 23, 2026 · graded Oct 23, 2026 by ToolGPA. Yellow Lab Tools is a free, GPL-licensed tool by web performance consultant Gaël Métais that loads one page in headless Chrome and scores it for performance and front-end code quality. Each rule gets a grade, the offending files or lines are listed, and the report shows how far the overall score would rise if the issue were fixed. It runs on a public website, as a command-line tool, or on your own server. - **Category:** Technical SEO & Site Audits - **Made by:** Gaël Métais - **Website:** https://yellowlab.tools - **Runs on:** Web, macOS, Linux - **Who should skip it:** Skip it if you need a whole site checked, as each run tests one page address. - **Facts last checked:** Oct 23, 2026 ## Pricing As of Oct 23, 2026, Yellow Lab Tools is free to use. - **Pricing model:** Free - **Free plan:** Entirely free: the public website, the API, the command-line tool and the self-hosted server, with donations through GitHub or Ko-fi. - **Free trial:** None listed. | Plan | Price | What you get | | --- | --- | --- | | Free | $0 | The public instance at yellowlab.tools, its REST API, the npm command-line tool and the open-source server. | Read from https://yellowlab.tools/about on Oct 23, 2026. Prices change, so confirm with Yellow Lab Tools before buying. ## Key features - **Scored page audit:** Gives a global score out of 100 and a grade per rule, grouped as network, images, DOM, JavaScript, jQuery, CSS, web fonts and server config. - **Offenders and score gain:** Each rule lists the files, selectors or functions at fault and says how many points the global score would gain if it were fixed. - **Device and access settings:** Simulates a phone, tablet or desktop, and can send cookies, basic HTTP login details or a proxy, or block and allow chosen domains. - **Public API:** A REST API on yellowlab.tools queues runs, reports their status and returns the full JSON result or parts of it, with CORS allowed. - **Command line and Node module:** Installed from npm, the yellowlabtools command tests a page and prints the result as JSON or XML, with an optional screenshot. - **Private server:** The server code can be installed on your own machine or run from a community Docker image, for testing pages on localhost or an intranet. ## Good for - Front-end developers tracing what makes a single page heavy or slow - Reviewing a page's JavaScript, CSS, images and fonts against good practice - Testing pages on localhost or behind a firewall with a private instance ## Worth knowing - Each run tests one page address; the documentation describes no site-wide crawl or scheduled monitoring. - The public instance queues runs and processes one at a time, so a test can wait behind others. - Self-hosting needs Node.js and is documented for Linux and macOS; the author says Windows is untested. - Under the GPL-2.0 license, changes to the code of a hosted copy must be published under the same license. ## ToolGPA grades **GPA: 3.2 out of 4**, graded Oct 23, 2026. Yellow Lab Tools loads one page in headless Chrome and grades its JavaScript, CSS, images, fonts and server settings, listing the files at fault and how many points each fix would add. It's free, but it tests one address at a time with no site crawl or scheduled monitoring, and runs on the public site can queue behind other people's. - **Value for money: A.** Free under the GPL-2.0 license: the public website, its REST API, the npm command-line tool and the server code. There's no paid plan; the author takes donations through GitHub or Ko-fi. - **Free plan and trial: A.** Every part is free, with no paid tier on record. The catch is the public instance, which processes one run at a time, so a test can wait in a queue. - **Features: C.** A score out of 100 and a grade per rule across network, images, DOM, JavaScript, CSS, fonts and server config, with the offending files listed. It does a one-page front-end audit fully, but that's a smaller job, with no site-wide crawl or monitoring described. - **Ease of use: B.** No rating on record. On the public site you give it a page address and a device type and wait for the report. Running your own copy is another matter: it needs Node.js, documented for Linux and macOS only. - **Platforms and integrations: B.** Web, with a public REST API that returns JSON, plus an npm command-line tool and a server you can run on Mac or Linux. No phone app, and no integrations on record. These are ToolGPA's own grades. Graded from this listing, whose facts were read from Yellow Lab Tools' own pages on 23 October 2026. Not based on using the product, and shorter than our full reviews. ## Where it stands among technical SEO tools - Yellow Lab Tools's GPA of 3.2 is higher than 81 of the 83 other technical SEO tools we grade, and level with 2. - It stands best on free plan and trial (A, above 62 of 83) and worst on features (C, above 10). - Yellow Lab Tools has no paid plan. - On features, ease of use and platforms it scores 2.7 out of 4, and no tool on the category's chart scores higher without costing more. The category's chart of price against score: https://toolgpa.com/charts/technical-seo ## Keep it, or make your own? **Keep it.** Yellow Lab Tools is free, so making your own would save you nothing. And it is not the kind of software a weekend replaces. It is one of the better ones too: its GPA of 3.2 is higher than 81 of the 83 other technical SEO tools we grade. - You could not: Speed tests run from real browsers on a schedule. - You could not: A real app for macOS and Linux. Something home-made would be a web page. - You could not: An API that other software can build on. A judgement by ToolGPA from this listing, by rules that are the same for every tool. Nothing was built to test it. **Tags:** Page speed, Open source, Self-hostable, Public API ## Alternatives - [WebPageTest](https://toolgpa.com/tools/webpagetest): Page speed tests from real browsers in locations around the world. [Compare](https://toolgpa.com/compare/webpagetest-vs-yellow-lab-tools) - [GTmetrix](https://toolgpa.com/tools/gtmetrix): Page speed testing with Lighthouse reports, monitoring and an API. [Compare](https://toolgpa.com/compare/gtmetrix-vs-yellow-lab-tools) - [PageSpeed Insights](https://toolgpa.com/tools/pagespeed-insights): Free Google speed test with real-user Core Web Vitals and Lighthouse. [Compare](https://toolgpa.com/compare/pagespeed-insights-vs-yellow-lab-tools) - [sitespeed.io](https://toolgpa.com/tools/sitespeed-io): Free open-source toolkit for testing and monitoring web performance. [Compare](https://toolgpa.com/compare/sitespeed-io-vs-yellow-lab-tools) - [Lighthouse](https://toolgpa.com/tools/lighthouse): Google's open-source audit of page speed, accessibility and SEO. [Compare](https://toolgpa.com/compare/lighthouse-vs-yellow-lab-tools) ## Sources The prices, plans, platforms and features above were read from these pages on Oct 23, 2026: - https://yellowlab.tools/about - https://yellowlab.tools/ - https://github.com/YellowLabTools/YellowLabTools - https://github.com/YellowLabTools/YellowLabTools/wiki/Public-API - https://github.com/YellowLabTools/YellowLabTools/wiki/Command-Line-Interface - https://github.com/YellowLabTools/YellowLabTools/wiki/Install-your-private-server - https://github.com/YellowLabTools/YellowLabTools/blob/master/lib/metadata/scoreProfileGeneric.json Page: https://toolgpa.com/tools/yellow-lab-tools Listed by ToolGPA (toolgpa.com).