# How Stably uses Kernel

**333x**: “cutting browser cold starts by 333x”

As published on [kernel.sh](https://www.kernel.sh/customers/stably), May 2026. Captured by usedby on 2026-10-25.

- Company: [Stably](https://www.usedby.ai/companies/stably.md)
- Tool: [Kernel](https://www.usedby.ai/tools/kernel.md)

## The use case: how Stably deploys Kernel

Stably runs its AI-driven end-to-end testing platform on Kernel's cloud browsers, replacing headless Chromium it self-hosted on AWS. It uses headful browser sessions for interactive test authoring with an AI agent and for large parallel test suites.

Summary written by usedby from the source page, in English. The figures are those of Kernel and Stably, not ours.

> browser cold starts that took 10-20 seconds on aws are now 30 ms. users can easily spin up hundreds of parallel headful browser sessions for test suites without worrying about performance.

- **30 ms**: “browser cold starts that took 10-20 seconds on aws are now 30 ms.”

> we evaluated many options, and kernel is the only one that could deliver the performance all of our customers' test suites required.
>
> Jinjing Liang, Co-founder & CEO

Source: [kernel.sh](https://www.kernel.sh/customers/stably), captured 2026-10-25.

## Other companies using Kernel

- [Felicity](https://www.usedby.ai/companies/felicity.md) — Confirmed
- [Flint](https://www.usedby.ai/companies/flint.md) — Confirmed
- [Rye](https://www.usedby.ai/companies/rye.md) — Confirmed
- [The Prompting Company](https://www.usedby.ai/companies/the-prompting-company.md) — Confirmed
- [Cash App](https://www.usedby.ai/companies/cash-app.md) — Observed
- [Claim Health](https://www.usedby.ai/companies/claim-health.md) — Observed

## What usedby checked

We compared the story with its live page on 2026-10-25.

- Checked: the figure 333x is printed word for word on the page, near the name of Stably.
- Checked: the passage quoted above is copied word for word from the page, near the name of Stably.
- Checked: the publication date is read from the page’s own metadata, never guessed.
- Checked: Stably uses Kernel. Confirmed line. Latest check across sources: 2026-10-25.
- Not checked: the result itself. We quote it; we did not measure it.

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Source: https://www.usedby.ai/case-studies/stably-kernel · How we check: https://www.usedby.ai/methodology