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If you want a Stably alternative that checks each coding-agent change inside the running app (requests, state, console) while it is being made, Reticle is built for that. If you want a Playwright suite generated and maintained for you, fast, Stably is the stronger choice.
What Stably does
Stably promises "80% test coverage in minutes, not months" and calls itself "AI agents for end-to-end testing" (stably.ai).
Its CLI plans tests, creates Playwright tests with reviewable steps, runs them in its cloud or your CI with traces and recordings, and proposes fixes when tests drift or flags product bugs. A visual editor keeps plain-English steps in sync with the Playwright code in Git. We found no MCP integration for coding agents.
Plans are Hobby at $0, Team at $60 a month, Growth at $250 a month and Enterprise custom (pricing). Stably is not open source; it is a YC W22 company.
What Reticle does
Reticle checks an AI coding agent's change and returns a pass or fail with evidence. It reads network calls, console, DOM and application state, and on React and Svelte it names the file:line to fix.
Your agent calls it over MCP from Claude Code, Cursor or Codex, and saved flows replay with no model in the loop. It works on your own app and on sites you don't own (its own browser, SDK injected); app state and file:line need the SDK in your build.
Stably vs Reticle at a glance
| Stably | Reticle | |
|---|---|---|
| Main output | A Playwright suite in your repo | A verdict with evidence for each check |
| Who uses it | Teams that want suites without hand-writing them | Your coding agent while it works, plus CI |
| How it sees the app | From outside, through Playwright | Inside the page: network, state, console, DOM |
| Maintenance | Proposes updates when tests drift | Saved flows with drift detection and self-heal |
| MCP for coding agents | Not found | Yes |
| Re-runs | Playwright runs in its cloud or your CI | Deterministic replay, 0% flake over 8 replays |
| Open source | No | SDK Apache-2.0; server FSL-1.1 |
| Pricing | $0, $60, $250/mo, Enterprise | Start free, no card; open-source SDK free |
Where Stably is the better choice
- You want a standard Playwright suite you own. Stably's output is Playwright code in Git that runs anywhere.
- You want coverage fast. Stably generates a broad suite quickly and imports plans from Jira and docs.
- You want a visual editor where non-engineers read and edit steps in plain English.
- You want traces and recordings from cloud runs without setting them up.
Where Reticle is the better choice
- Your agent writes the code. The agent verifies its own change in the same session over MCP and fixes the
file:linebefore it says done. - The bug is not on the page. A double request, a 200 that never persists or a silent console error passes a Playwright test that reads the page. Reticle reads them.
- You want measured results. 85 of 88 seeded bugs caught with no false alarms, and about 480 tokens to re-verify a four-flow suite (benchmark scorecard).
Can you use both?
Yes. Stably can build and maintain the Playwright suite, and Reticle can check each agent change underneath the screen before that suite runs. The difference between a passing assertion and proven behaviour is covered in why a green check isn't proof.
For Playwright itself and other AI test generators, see the Playwright alternative and the alternatives hub.
Try Reticle
Paste one line to your coding agent and it installs and wires the SDK:
Follow https://raw.githubusercontent.com/reticlehq/reticle/main/SKILL.md
Or run npx @reticlehq/core init. The README has the details.
FAQ
What is the best alternative to Stably?
The best alternative to Stably depends on what you want delivered. For a check your coding agent runs inside the app, reading network, state and console, Reticle fits. For writing Playwright tests yourself, use Playwright. For another service that generates and maintains a suite, compare AI test generation tools.
How much does Stably cost?
Stably's plans were Hobby at $0, Team at $60 a month, Growth at $250 a month and Enterprise custom, as listed on its pricing page in October 2026. Reticle's SDK is free and open source under Apache-2.0, and its hosted platform can be started free with no credit card.
How is Reticle different from Stably?
Reticle is different from Stably in what it hands you. Stably generates Playwright tests that check the app from outside. Reticle gives your coding agent a pass or fail with evidence from inside the running app, including requests, state and console, and points to the source line on React and Svelte.
Does Stably work with Claude Code or Cursor?
We found no MCP integration for Stably's testing product when checked in October 2026; it runs as a CLI, a cloud and in CI. Reticle ships an MCP server for Claude Code, Cursor and Codex, and a skill file your agent follows to install and wire it into your app.
Why Reticle
Your agent says it works. Reticle checks.
- Checks each change inside the running app: network, state and console, not a screenshot.
- Returns a pass or fail with the evidence and the file:line to fix.
- Open-source SDK on your machine, or the platform on every preview and PR.
No credit card required.