Tesser
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The development runtime for coding agents

Tesser is a CLI that gives every worktree a cloud machine to run dev servers, typechecks, and tests on. View any server through our automatic proxying, or hand it off to a teammate without a separate deployment.

curl -fsSL https://tesser.sh/install | sh

Or set it up with your agent:

Built for teams of devs and agents

Port forwarding to localhost

Every port your app uses is forwarded to your laptop, so the dev server on the machine opens at localhost:3000 like it always has. Hot reload and sign-in cookies keep working, and a panel on the page switches between branches.

Local and cloud agents

Claude Code and Codex run tesser from your laptop. Cloud agents like Devin and Capy run it with an API token and get the same machines.

  • Claude Code
  • Codex
  • Gemini CLI
  • Copilot
  • Cursor
  • Devin
  • Capy

Your existing setup

Tesser starts your app with the install and dev commands you already use. Every machine comes with Node and Docker, so most stacks run as they are.

  • Next.js
  • Vite
  • Node.js
  • Bun
  • Docker
  • Postgres
  • Redis
  • Python

Bring your own compute

tesser cloud connect moves every machine into your own AWS account, inside your VPC and on your AWS bill. We host only the control plane.

~/acme
$

Set up in less than a minute

  1. One command installs tesser, and tesser login signs you in through the browser.

    Quickstart
    ~/acme
    $

  2. tesser skill install gives Claude Code and Codex a short skill that points them at tesser --help. From then on your agent runs the commands itself.

    Coding agents

  3. A short TOML file in the repo lists your app's ports and the install and dev commands you already use. Commit it once and every worktree can use it.

    Manifest reference

  4. Your agent runs tesser dev web in its worktree. The dev server comes up on that worktree's machine, and you open it at localhost:3000.

    Open a box in your browser

Flexible by design

Parallel coding agents

Every agent gets its own worktree and machine, so five agents on one repo never fight over port 3000 or your laptop's CPU.

Preview links

Put a link to your running branch in the PR. A reviewer opens it at box_7f3a91.localhost:3000 and tries the change before reading the diff.

Tests and builds

tesser exec -- pnpm test runs the suite on the worktree's machine. The output and exit code come back as if it ran locally.

Claude Codelaptop
$ tesser exec -- docker compose up -d
✔ Network workspace_default Created
✔ Container workspace-db-1 Started
✔ Container workspace-redis-1 Started
$ tesser exec -- pnpm test:integration
Tests 86 passed (86)

Apps with a database

Each branch runs its own Postgres and Redis with Docker Compose, so one branch's migrations never touch another's data.

Get started

Install the CLI and follow the quickstart to get your first cloud environment up and running.

curl -fsSL https://tesser.sh/install | sh

Or set it up with your agent:

Sign upRead the docs