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If you want a Thunders alternative that a developer starts free and that reads what each step did inside the app, in the coding agent's loop, Reticle is built for that. If you want AI test agents that run one journey across web, mobile, API, desktop and enterprise systems, Thunders is the stronger choice.
What Thunders does
Thunders, formerly Thunder Code, says "AI Test Agents build, run and maintain your end-to-end tests across web, mobile, API and desktop. One journey, every system. Under 0.5% flaky runs" (thunders.ai). The flaky-run figure is the vendor's own claim.
It turns requirements into test journeys, runs a single journey across web, mobile, API, desktop and enterprise systems, and reports evidence. Every tier includes a Thunders MCP server and CI/CD integrations, and the pricing page pitches "Bring your Playwright, keep Claude".
Pricing is public: Starter $479 a month ($375 billed yearly) with 300 credits, Pro $1,199 a month, Enterprise custom (pricing, checked 2026-10-25). It is not open source.
What Reticle does
Reticle checks an AI coding agent's change from inside the running web app and returns a verdict with evidence. It reads the network calls, the application state and the console, and on React and Svelte it names the file:line to fix.
Your agent calls it through MCP while it works. Flows are saved and replay deterministically, with no model in the loop. It also drives sites you do not own, reading network, console and DOM there. The SDK is open source (Apache-2.0); the hosted platform runs the same checks on previews and pull requests.
Thunders vs Reticle at a glance
| Thunders | Reticle | |
|---|---|---|
| How tests are made | AI agents turn requirements into journeys | Your coding agent drives flows, saved and replayed |
| Surfaces | Web, mobile, API, desktop, enterprise systems | Web apps |
| What a step checks | The journey's outcome and evidence | Network count, app state, console and DOM after each step |
| MCP | Yes, every tier | Yes, for Claude Code, Cursor, Codex |
| Apps you do not own | Yes | Yes (no app state or file:line) |
| Points to the fix | The failing journey step | The failing request or state, and file:line on React and Svelte |
| Open source | No | SDK Apache-2.0; server FSL-1.1 |
| Pricing | From $479/month | Start free, no card; open-source SDK free |
Where Thunders is the better choice
- One journey crosses many systems. A flow that starts on mobile, calls an API and ends in a desktop or enterprise app is what Thunders is built for. Reticle covers web apps.
- Tests should start from requirements. Thunders turns requirements into journeys, which suits PMs and QA leads.
- You want a managed, credit-based service. Plans bundle the agents, runs and MCP server.
- You already have Playwright tests to keep. Thunders says it works alongside existing Playwright.
Where Reticle is the better choice
- The failure is under the screen. A double request, a write that never persists, a store that disagrees with the page. Reticle reads those after each step, so they fail even when the screen looks right.
- The coding agent should verify its own change. Reticle runs in the agent's loop and names the source line on React and Svelte, so the fix happens before review.
- Re-runs are deterministic, by construction. Replay has no model in the loop: eight replays of a saved flow gave one verdict. Re-verifying four flows costs about 480 tokens.
- You want to start free. The SDK is open source and local; no credits to buy to begin.
On 88 seeded bugs, Reticle caught 85 with no false alarms (benchmark scorecard).
Can you use both?
Yes. Thunders can own cross-system journeys for a QA or product team. Reticle checks each agent-written change inside your web app before those journeys run.
For why an agent's "done" needs evidence, read why a green check isn't proof. Related pages: the Momentic alternative, the QA Wolf alternative, and all alternatives.
Try Reticle in five minutes
Paste one line to your coding agent, and it installs and wires the SDK in your app:
Follow https://raw.githubusercontent.com/reticlehq/reticle/main/SKILL.md
Or run npx @reticlehq/core init yourself. The README has the details.
FAQ
What is the best alternative to Thunders?
The best alternative to Thunders depends on the job. For a coding agent verifying its own changes inside a web app, reading network, state and console, Reticle fits. For another AI agent platform covering mobile and API journeys, compare tools such as Momentic or mabl. For hand-written tests, Playwright fits.
How much does Thunders cost?
Thunders Starter costs $479 a month, or $375 billed yearly, with 300 credits, and Pro costs $1,199 a month, with Enterprise custom, as of October 2026. Every tier includes its MCP server. Reticle lets you start free with no card, and its in-app SDK is open source.
How is Reticle different from Thunders?
Reticle is different from Thunders in scope and depth. Thunders runs AI-built journeys across web, mobile, API and desktop systems. Reticle focuses on web apps and reads requests, application state and console from inside the page, then replays saved flows with no model in the loop.
Is Thunder Code the same as Thunders?
Yes, Thunders is the current name of Thunder Code, a Paris company founded in 2024, according to its PitchBook profile. The product is AI test agents for end-to-end testing across web, mobile, API and desktop. Reticle is an open-source alternative focused on verifying agent changes inside web apps.
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.