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A11y PulsevsSiteimprove Alfa

Alfa is the engine.
A11y Pulse is the whole car.

Siteimprove's Alfa is a free, open-source engine for building accessibility checks into your own tools. A11y Pulse is a hosted service that scans your whole site every day, with alerts and reports included.
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What is Alfa?

Siteimprove describe Alfa as "an open and standards-based accessibility conformance testing engine." It implements the W3C Accessibility Conformance Testing (ACT) rules format and is the engine behind Siteimprove's commercial accessibility product. If you are evaluating that product, see our Siteimprove comparison.

CLIAudit a single page
A command-line interface for running Alfa's rules against one page, with a crawler to discover linked pages.
IntegrationsTest frameworks
Maintained integrations for Cypress, Playwright, Puppeteer, and WebdriverIO, with others for Jest, Vitest, and component libraries marked experimental.
OutputEARL results
Results are published in the W3C EARL format as JSON-LD, ready for other tools to consume.

Side by side

A11y Pulse vs Alfa

Pricing
Testing engine
WCAG 2.2 A and AA criteria checked
Interaction audits
Setup time
Page discovery
Scheduling
Regression alerts
Stakeholder reports
Test-framework integrations
Best for
A11y PulseContinuous, site-wide
Recommended
$19, $49, $159 / monthHosted, monthly billing
axe-core + A11y Pulse auditsOur own audits interact with pages how real users would
28 of 55 today39 planned by the end of 2027
Included
About 5 minutesNo maintenance required
Sitemap, crawl, or URL list
Daily, with unlimited rescans
Email, Slack, Teams
PDF report and monthly email
CI integration and RESTful API
Teams who want site-wide monitoring without running it themselves
AlfaOpen-source engine
For comparison
FreeMIT licensed, plus your hosting costs
AlfaBuilt on W3C ACT rules
19 of 55
Not offered
Engineering projectPlus ongoing maintenance
Built-in crawlerYou run and schedule it
Build it yourself
Build it yourself
Build it yourselfResults output as EARL JSON-LD
Cypress, Playwright, Puppeteer, WebdriverIOMore integrations marked experimental
Developers embedding ACT-based checks in their own tooling

WCAG coverage

A11y Pulse checks more WCAG criteria than Alfa

A11y Pulse automatically checks 28 of the 55 WCAG 2.2 Level A and AA success criteria today, compared with 19 for Alfa. Our roadmap takes that to 39 by the end of 2027.

That will put A11y Pulse ahead of every tool we have measured.

No automated tool can check every criterion. Use A11y Pulse alongside thorough manual testing to help you work towards WCAG compliance. See how we measured coverage.

WCAG 2.2 Level A and AA success criteria checked by each tool, out of 55
ToolSuccess criteria checked
A11y Pulse today
28 of 55 (51%)
A11y Pulse in 2027
39 of 55 (71%)
Alfa
19 of 55 (35%)

Alfa: @siteimprove/alfa-rules 0.119 active rules, excluding media rules that need a reviewer to answer questions. Measured in October 2026.

Why teams switch to A11y Pulse

Three things you get when the engine comes hosted

Alfa is free and standards-based, but it is an engine. Scheduling, storage, alerting, and reporting are left to whoever wires it up.

1

Operations

No pipeline to maintain

Running Alfa across a site means a crawler, a scheduler, somewhere to store results, and someone to keep the dependencies current. A11y Pulse does all of that for you, so setup takes minutes rather than a sprint.

Five-minute setup

2

Alerting

Regressions come to you

Alfa reports what it finds when you run it. A11y Pulse runs every day and tells you by email, Slack, or Teams when a scan finds something new, whether the change came from code, content, or a third-party script.

Email, Slack, Teams

3

Reporting

Results people can act on

Alfa outputs machine-readable EARL results. A11y Pulse groups issues in a dashboard, tracks trends over time, and produces PDF reports and monthly digests for stakeholders.

Dashboard, PDF, monthly digest

Where we fit

Everything around the engine, already built

A11y Pulse runs axe-core, the industry-standard engine, plus our own audits that interact with pages how real users would. The difference from Alfa is everything around the engine: page discovery, daily scheduling, a dashboard, alerting, and reporting are all included.

  • axe-core plus our own audits, in a real Chrome browser across your entire site
  • Scripted login flows for authenticated pages
  • Email, Slack, and Microsoft Teams alerts when something regresses
  • MCP server so Claude and Cursor can access your scan results and fix your issues
The A11y Pulse dashboard showing daily scan results across multiple pages with a 30-day trend chart.

The verdict

When each tool is the right call

Choose

A11y Pulse

  • You want daily scans of your whole site without building a pipeline
  • You need alerts when something regresses on the live site
  • Stakeholders need reports, not machine-readable results
  • Your team doesn't have spare capacity to operate accessibility tooling
  • You want a dashboard that groups issues and tracks trends

Choose

Alfa

  • You want a free, open-source engine to build your own tooling on
  • Conformance with the W3C ACT rules format matters to your team
  • Accessibility assertions inside your Cypress or Playwright tests are the priority
  • You already have infrastructure for scheduling, storage, and reporting
  • You plan to buy Siteimprove's commercial platform, which uses the same engine

The information presented here about A11y Pulse and Alfa is provided for comparison purposes and may change over time. Pricing and feature claims about Alfa should be verified on their own website before making a purchasing decision.

Accessibility monitoring without the plumbing

30-day free trial, no credit card. Daily scans across your whole site, with alerts and reports included.
Start your free trial