Lark

Lark builds an end-to-end testing layer aimed at AI-assisted software development. Teams describe tests in plain English rather than writing test code, and Lark's agents execute them against dashboards, API endpoints, SDKs, and multi-step product flows, including asynchronous workflows. Tests can be run continuously on feature branches, inside CI, or against production environments.

The product is delivered as a hosted service with a CLI (npx/npm package @getlark/cli, requiring Node.js 18+) and a dashboard for API key management. The CLI organizes tests as "workflows" that can be created, updated, grouped, archived, invoked in bulk and polled for results, with exit codes designed for CI gating. Workflows run in either an "ai_driven" or "deterministic" mode, support cron schedules and named secret contexts, and produce executions, generations (the background process that compiles a workflow into an executable artifact) and repairs (AI-driven repair attempts after a failed execution). Failures return logs, screenshots, videos and reproducible test scripts.

Integrations include native support for GitHub Actions, GitLab CI and other CI tools, alerting through Slack, email and PagerDuty, and the ability to block pull requests from merging when tests fail. Lark also publishes agent skills and a CLI for coding agents such as Claude Code, Cursor and Codex, plus open-source components from its engineering team including runtimeuse (running AI agents in sandboxes over WebSockets) and previewuse (automated preview environment generation).

Founding story

Lark was founded in 2025 by Vijit Dhingra and Jack Brown, who met as engineers working on usage-based billing at Stripe. Dhingra spent five years at Stripe as a tech lead building its usage-based billing product and other payments infrastructure, and contributed to internal testing infrastructure intended to improve developer productivity and product reliability. Brown also built usage-based billing at Stripe for the pricing models of large AI companies, and previously led engineering teams at startups where he worked on developer tooling infrastructure.

Business model

Lark sells testing infrastructure to engineering organizations as a hosted product, accessed via a dashboard, API keys and a CLI, with website calls to action directed at booking a demo.

Traction

Y Combinator lists Lark as an active Summer 2025 company with a team size of 5. Public GitHub repositories from the organization show modest community traction (openlily 26 stars, runtimeuse 10 stars, previewuse 7 stars) with commits through 2026, and the company publishes public sample test runs for at least one customer-facing example.

Latest developments

Publication of a CLI and documentation covering workflow groups, scheduled runs, secret contexts, AI repairs and asynchronous bulk jobs such as workflow import, alongside agent skills that let coding agents author, run and manage end-to-end test workflows. Repository activity in the company's GitHub organization continues into 2026.