Skip to content
ToolGPA

Yellow Lab Tools review (2026): is it any good?

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

FreeTechnical SEOChecked Oct 23, 2026 · graded Oct 23, 2026 by ToolGPA
Visit yellowlab.toolsFree guide

Yellow Lab Tools report card

3.2GPA

Very good · out of 4.0 · graded Oct 23, 2026

Best for auditing one page's front-end code for free

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.

Who Yellow Lab Tools is for

  • Fits if you're a front-end developer tracing what makes one page heavy or slow
  • Works for testing pages on localhost or an intranet through a private copy

Who Yellow Lab Tools is not for

  • Skip it if you need a whole site checked, as each run tests one page address
  • Not for you if you want ongoing monitoring, since no scheduled tests are described
  • Watch out: the public site processes one run at a time, so a test can wait behind others
  • Tight if you self-host on Windows, which the author says is untested; Linux and macOS are documented
  • Watch out: under GPL-2.0, changes to a hosted copy's code must be published under the same license
See the alternatives

Why Yellow Lab Tools gets a 3.2

Five grades, each with its reason. The GPA is their average: an A is 4 points, an F is none.

  • AValue for moneyFree 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.
  • AFree plan and trialEvery 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.
  • CFeaturesA 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.
  • BEase of useNo 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.
  • BPlatforms and integrationsWeb, 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.

What these grades rest on. 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. How we review and grade.

Make Yellow Lab Tools? Put this grade on your site
Yellow Lab Tools: 3.2 GPA on ToolGPA

Paste this where you want the badge. It links here and follows the grade if it changes. About badges

<a href="https://toolgpa.com/tools/yellow-lab-tools#review"><img src="https://toolgpa.com/badge/yellow-lab-tools.svg" alt="Yellow Lab Tools: 3.2 GPA on ToolGPA" width="196" height="56"></a>

Where Yellow Lab Tools 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.

Each grade against the category

Every bar is all 84 technical SEO tools we grade, cut by the letter each got. Yellow Lab Tools’s own letter is outlined.

  • AValue for moneyAbove 54 of 83, level with 29
  • AFree plan and trialAbove 62 of 83, level with 21
  • CFeaturesAbove 10 of 83, level with 66
  • BEase of useAbove 62 of 83, level with 21
  • BPlatforms and integrationsAbove 27 of 83, level with 56

Price against what you get

Each dot is one of 73 technical SEO tools. Further left costs less, and higher up scores better on features, ease of use and platforms. Point at a dot to see which tool it is.

Features, ease of use and platforms, averaged

D1.0C2.0B3.0A4.0Free$2$5$10$20$50$100$200$500$1k$2k$5kMore for lessCosts more, scores moreCosts less, scores lessCosts more, scores lessYellow Lab Tools

What paid plans start at, a month (each step along is roughly double) →

  • The best score at each price
  • Has a free plan
  • No free plan
The full chart, and the best technical SEO tools at every price

Keep Yellow Lab Tools, 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.

What you could not

  • Speed tests run from real browsers on a schedule.
  • A real app for macOS and Linux. Something home-made would be a web page.
  • An API that other software can build on.

What this rests on. Yellow Lab Tools’s listing: what it does, where it runs, what it plugs into and what it costs. It is a judgement about the kind of software this is. We have not built a replacement for it, and making your own means looking after it too. How we decide, and every tool’s verdict.

What is Yellow Lab Tools?

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.

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.

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.

Yellow Lab Tools pricing

As of Oct 23, 2026, Yellow Lab Tools is free to use.

Starts at
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
Free$0The public instance at yellowlab.tools, its REST API, the npm command-line tool and the open-source server.

Read from yellowlab.tools on Oct 23, 2026. Prices change, so confirm with Yellow Lab Tools before you buy.

Pricing in detail

Yellow Lab Tools alternatives

All Yellow Lab Tools alternatives comparedAll technical SEO tools

Common questions

Does Yellow Lab Tools have an Android app?

No Android app was listed when its pages were read on Oct 23, 2026. Yellow Lab Tools is listed for Web, macOS and Linux.

Does Yellow Lab Tools have an iPhone app?

No iPhone app was listed when its pages were read on Oct 23, 2026. Yellow Lab Tools is listed for Web, macOS and Linux.

Is Yellow Lab Tools open source?

Yes. Yellow Lab Tools is open source, according to its own site. It can also be run on a server of your own.

Does Yellow Lab Tools have an API?

Yes. Yellow Lab Tools offers a public API, according to its own site.

Sources for this page

The prices, plans, platforms and features above were read from these pages on Oct 23, 2026.