GTmetrix vs Yellow Lab Tools (2026): which should you pick?

Pick GTmetrix if

• Fits if you want a Lighthouse report with a load video for a page now and then
• Works for developers who want to start speed tests from their own code through the API

Look elsewhere if

• Tight if you watch many pages, as Lite monitors 1 and Core 3, and hourly checks start on Advanced at $24.99 a month
• Pricey if a team shares it, as seats start on Expert at $49.99 a month yearly, and white-label PDFs are Enterprise only at a quoted price
• Tight if you stay on Basic or Lite: Basic runs 2 API tests at a time against 8 for most PRO users, and Lite gets the API only as a 10-credit trial
• Watch out: API tests spend credits, a video costs 0.9 more, and credits refill daily only up to the plan's allowance
• Watch out: API reports are kept 1 month unless you pay credits for up to 24, and refunds become account credit after 14 days

Pick Yellow Lab Tools if

• 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

Look elsewhere if

• 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

GTmetrix

• Team seats start only on Expert ($49.99 a month billed yearly), and hourly monitoring on Advanced; refunds are promised for 14 days, after that only account credit.
• API tests run on credits: a Lighthouse report costs 1 credit, a video 0.9 more, and credits refill daily only up to the plan's allowance.
• Through the API, Basic accounts can run 2 tests at once, against 8 for most PRO users.
• API reports are kept 1 month unless longer retention, up to 24 months, is paid for in extra credits.

Yellow Lab Tools

• 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.

GTmetrix

Lighthouse speed reports

Each test produces a Lighthouse report, with older PageSpeed and YSlow reports or a metrics-only report also available through the API.

Locations, browsers and devices

Choose the test location and browser, simulate phones and tablets by screen size and pixel ratio, and throttle the connection speed.

Videos and PDF reports

Record a video and filmstrip of the page loading, and export a summary or full PDF of the report.

Page monitoring and alerts

Monitored pages are retested on a schedule, grouped with tags, and can raise performance alerts when chosen metrics cross set conditions.

REST API

Start tests, fetch reports and manage monitored pages from your own code, with an OpenAPI specification and a GTmetrix for WordPress plugin.

Yellow Lab Tools

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.

GTmetrix

• Lite$4.99

  per month, billed yearly ($5.99 billed monthly)

  50 on-demand tests a month, 1 monitored page, 5 test locations, 1 month of history. API and MCP only as a 10-credit trial; no hourly monitoring.

• Core$9.99

  per month, billed yearly ($11.99 billed monthly)

  150 tests a month, 3 monitored pages, 10 locations, 10 API credits a day and 6 months of history. No hourly monitoring or team seats.

• Advanced$24.99

  per month, billed yearly ($29.99 billed monthly)

  Unlimited on-demand tests under a fair-use rule, 10 monitored pages with hourly checks, 28 locations and 50 API credits a day.

• Expert$49.99

  per month, billed yearly ($59.99 billed monthly)

  50 monitored pages, 100 API credits a day, 12 months of history and 5 team seats. Enterprise adds white-label PDFs at a quoted price.

Yellow Lab Tools

• Free$0

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