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testcritic

Biome vs DeepSource

Feature checklists rarely decide anything. What decides it is the pricing metric, who has to write the tests, and which limitation you can live with.

Entry price

Free and open source

Open source

From $24 per user/month (Team, billed yearly)

Free tier

What drives the bill

The metric that actually scales your invoice.

Free and open source. You pay in engineering time and CI minutes.

Team includes a $100 annual AI Review credit per user; Enterprise adds self-hosting and SSO on a quote.

Free tier

Everything, self-hosted

Free for public repositories, with 1,000 PR reviews a month; 14-day trial plus AI Review credits on paid plans.

Open source

MIT

Self-hostable

No-code authoring

Languages

JavaScriptTypeScript
PythonJavaScriptTypeScriptGoJavaRubyPHPC#KotlinSwift

Platforms

WebAPI
WebAPI

Fits teams

Solo / side projectStartupScale-up / mid-market
Solo / side projectStartupScale-up / mid-market

Adoption

Widely used

Biome / OSS community · since 2023

Established

DeepSource · since 2019

Strengths

  • Dramatically faster than ESLint plus Prettier, which matters on pre-commit hooks.
  • One binary and one config replaces two toolchains.
  • Very good ESLint rule migration tooling.
  • Autofix commits remove the tedious half of acting on findings.
  • Low false-positive rate keeps developers engaged with the tool.
  • Cheap and quick to adopt.

Limitations

  • Rule coverage does not yet match ESLint's plugin ecosystem.
  • No support for framework-specific plugin ecosystems at ESLint's depth.
  • Young project, so expect churn.
  • Narrower language coverage than SonarQube.
  • Smaller vendor with less enterprise governance tooling.
  • Autofix still needs review — it is not unattended.

Best for

New JavaScript projects and teams frustrated by lint performance.

Teams that want static analysis developers do not resent.

Pricing last reviewed August 2026 and is indicative only — confirm on each vendor’s own page.