Alfa

Alfa is an open-source accessibility conformance engine for websites built with HTML, CSS, and JavaScript. It is best suited to developers who want to build accessibility checks into their own tools and workflows. Its adaptable rules and audit options are valuable, but teams should weigh those against the experimental status of most integrations.

Overview

Alfa checks web content against accessibility standards, including WCAG 2.2. Its default rules are WCAG-based and follow the ACT Rules Format; developers can add rules and filter results by conformance level or WCAG version. That flexibility makes it a practical fit for teams tailoring checks to a codebase, rather than seeking a standalone audit interface.

Audit output follows the Evaluation and Report Language (EARL) Schema in JSON-LD, and the CLI can save a single-page audit as JSON. These structured outputs suit workflows that consume machine-readable results. Alfa is distributed as separate npm packages under the MIT license. Siteimprove says code that can affect test results resides within Alfa, rather than with a third party, which may matter to teams reviewing their testing dependencies.

Key features

Page and site audits: A scraper fetches a page representation for auditing; a crawler discovers and scrapes linked pages across a site or subdomain. The CLI offers a focused single-page check, while crawling can broaden coverage beyond an individual URL.

Developer integrations: Packages cover Angular, React, Vue, Cypress, Jest, Playwright, Puppeteer, Selenium, and WebdriverIO, among others. This breadth can help teams incorporate checks into existing development and test workflows, but most integrations are experimental and may change.

Custom rules and filtering: Teams can extend the default WCAG-based rule set and filter results by conformance level or WCAG version. This is useful when checks need to reflect a particular project’s criteria, though it requires developers to own that configuration.

Runtime: Alfa runs in ECMAScript 2022-compatible JavaScript environments, including recent Node.js and major browser versions. Building from source requires Node.js 20 or later and Yarn; older environments may be targetable from source but are not explicitly supported.

Pricing

Alfa is free: its plan costs nothing and includes open-source software under the MIT license, distributed as separate npm packages. There are no paid tiers described. The trade-off is that teams adopting it take on integration and configuration work, especially where experimental packages are involved.

Platforms

Alfa is available for API, Linux, macOS, self-hosted, web, and Windows use. Its runtime requirement is ECMAScript 2022-compatible JavaScript, including recent Node.js, Chrome, Firefox, Safari, and Edge versions. The project does not explicitly support older environments.

Who it's for

Alfa is a strong choice for development teams that want standards-based accessibility checks in code, CI/CD, or browser automation workflows, and value custom rules or structured audit output. It is less suitable for buyers seeking a finished, standalone audit interface or teams that need integrations to be stable and fixed.

Pros and cons

Pros: WCAG-based rules, WCAG 2.2 coverage, and support for custom rule implementations give teams room to shape their checks.

Pros: The CLI, scraper, crawler, and developer packages support both focused page audits and broader workflow integration.

Pros: Free, MIT-licensed distribution lowers the cost barrier and permits use and modification under that license.

Cons: Most integrations are experimental and subject to change, so teams may need to absorb maintenance as workflows evolve.

Cons: Building from source requires Node.js 20 or later and Yarn, while older environments are not explicitly supported.

Alternatives

For a different category of software, Accessibility Testing Software is the relevant list. The other linked options are terminal file managers, not accessibility testing engines: FileManagerTUI is free, open source, and runs on Linux, macOS, and Windows; nnn is a free open-source terminal file manager for Android and desktop platforms; Rat Commander is a free, self-contained terminal file manager for Linux, macOS, and Windows; Newt is free, open source, and supports Linux, macOS, and Windows; superfile is a free, MIT-licensed, self-installed terminal application; Broot is MIT-licensed, with source and precompiled binaries for Linux, macOS, and Windows; elio is free and supports Linux, macOS, self-hosted, and Windows; and far2l is a free GNU/GPLv2 option for Linux and macOS in beta, with use at your own risk.

Verdict

Choose Alfa if you want a free, extensible accessibility engine that can put WCAG checks into developer workflows and produce structured results. Look elsewhere if your decision depends on stable integrations or a standalone audit experience; Alfa’s flexibility comes with integration work and experimental packages.