AI agents for testing
Agents that write unit tests, run your suite, fix what fails and click through your app like a QA engineer.
By weekly package downloads, the leaders are Claude Code (14.8M), Stagehand (2.5M), Amazon Nova Act (71.7K). By VS Code extension installs, the leaders are GitHub Copilot (78.6M), Claude Code (27.1M). By GitHub stars, the leaders are Claude Code (150K), Aider (49.4K), Stagehand (25.5K). The fastest grower over the last 30 days is Stagehand, with downloads up 16%. As of Oct 6, 2026.
| # | Agent | Category | Pulse | Downloads 7d | 7d | 30d | VS Code installs | Stars | Latest release | Price | Last 90 days |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 3 |
Claude CodeAnthropic |
Terminal | 80 | 14.8M | up 11.6% | down 36.4% | 27.1M | 150K+161/day | 2.1.290yesterday | $20/mo | |
| 9 |
GitHub CopilotGitHub (Microsoft) |
IDEs | 70 | — | — | — | 78.6M | — | — | Free + $10/mo | |
| 20 |
StagehandBrowserbase |
Browser | 58 | 2.5M | up 13.4% | up 16.5% | — | 25.5K+15/day | 3.7.339d ago | Free + $20/mo | |
| 31 |
DevinCognition |
Cloud | 53 | — | — | — | — | — | — | $20/mo | |
| 84 |
AiderAider-AI (Paul Gauthier) |
Terminal | 34 | 61.3K | down 1.5% | down 57.8% | — | 49.4K+23/day | 0.86.014mo ago | Free (OSS) | |
| 111 |
Amazon Nova ActAmazon (AWS) |
Browser | 23 | 71.7K | down 3.5% | down 41.0% | — | 918 | 3.4.187.05mo ago | Usage-based | |
| 141 |
Claude in ChromeAnthropic |
Browser | 2 | — | — | — | — | — | — | $20/mo | |
| No agents match that filter. | |||||||||||
Ranks are overall positions by Pulse Score. Click a column to sort by what matters to you. Methodology.
Two kinds of testing agent
Coding agents write and run tests in your repository: they read the code, add unit and integration tests, run the suite and iterate on failures. Browser agents test the running application from the outside, following a user flow described in plain language. The first raises coverage; the second catches what only shows up in a real browser.
What each agent does for this task
Only agents whose own documentation describes this use are listed. Checked Oct 6, 2026.
| Agent | What it does | Source |
|---|---|---|
| GitHub Copilot | Generates unit and integration tests, including edge cases and exception handling | docs |
| Claude Code | With Chrome connected, tests local web apps: form validation, visual regressions, user flows and console errors | docs |
| Aider | Runs your test command with /test or --auto-test and tries to fix the failures | docs |
| Devin | Analyses a test suite, writes new tests to raise coverage and verifies them by running the suite | docs |
| Claude in Chrome | Browser extension that Claude Code drives to test web apps and check user flows in a live browser | docs |
| Amazon Nova Act | UI tests defined in natural language, with visual logs of each run | docs |
| Stagehand | Runs end-to-end browser tests with Stagehand or Playwright in isolated cloud browsers | docs |
Keep the tests honest
- Watch for tests that test nothing. An agent asked to make tests pass can weaken assertions or mock away the code under test. Review the assertions, not just the green tick.
- Pin the behaviour first. Ask the agent to write a failing test that reproduces a bug before it fixes it.
- Browser tests are slower and flakier than unit tests; keep them for the flows that matter most.
More options by job: the best AI agents in every category.