Coasts

Coasts runs multiple isolated development environments for the same project on one machine. Each environment can use its own ports, network, and services, with configurable sharing for resources such as volumes and services. Running environments receive dynamic ports, while the checked-out environment uses the project’s canonical ports. Coasts supports Docker Compose projects and local development setups without containers, and works with Git worktree-based agentic coding workflows without special harness-side configuration. Its documentation lists Codex, Claude Code, Cursor, Conductor, T3 Code, and Shep as supported harnesses. Services can also run on SSH-reachable remote machines alongside local environments. Coasts is free, open source under the MIT license, and described as offline-first with no hosted service dependency. It runs on macOS and Linux and requires Docker, Git, Node.js, and socat. On Linux, binding canonical ports below 1024 may need additional host configuration.

Coasts provides isolated local environments with optional shared resources and remote SSH runtimes. Confirm its system requirements and Linux port setup against your development environment.

Coasts suits developers working on several Git worktrees or agentic coding tasks who need separate local runtimes. It also supports teams combining local development environments with services on remote SSH-accessible machines.

Coasts is a local development environment manager for running multiple isolated versions of one project on the same machine. It suits developers working across Git worktrees, especially with AI coding tools. Its strongest case is flexible isolation without a hosted-service dependency; setup requires several local tools, and Linux users may need extra port configuration.

Overview

Each environment, called a Coast, gets its own ports, network and services. Configurable sharing lets developers reuse selected resources while keeping other data separate, a practical balance for parallel work that needs distinct application instances without duplicating every database or cache.

Coasts supports Docker Compose projects and non-containerized local development. It is designed for agentic workflows built around Git worktrees, with no special harness-side configuration required. Documentation covers Codex, Claude Code, Cursor, Conductor, T3 Code and Shep.

The project is described as free, local, offline-first and MIT-licensed, with no hosted-service dependency or AI upsells. That model will appeal to developers who want environments to stay on their own machines. It also means Coasts depends on a locally prepared development stack.

Key features

Parallel worktree environments

Separate ports, networks and services reduce collisions when several branches run at once. Running Coasts receive dynamic ports, while the checked-out Coast keeps the project's canonical ports. That makes it easier to use the expected project URLs in the active environment while other instances run alongside it.

Configurable resource sharing

Shared services, shared volumes and per-instance data isolation let developers choose how databases and caches behave across environments. This flexibility is useful when some state can be reused but branch-specific data must stay separate. It does require choosing a sharing strategy that fits the project.

Secrets and remote runtimes

Coasts can take secrets from the host environment and inject them into Coast containers, so credentials do not need to be hardcoded in a Coastfile. Remote Coasts run services on machines reachable over SSH, and can be combined with local runtimes. This gives resource-heavy services a route to remote hardware while keeping some work local.

Workflow and stack compatibility

Support for Docker Compose and non-containerized setups makes Coasts relevant beyond projects already packaged as Compose stacks. Its documented harness support spans several coding tools, while the no-special-configuration approach keeps the workflow centered on Git worktrees rather than a separate harness setup.

Pricing

The Coasts plan costs nothing. It is free, local and open source, with no usage limits stated and no free trial because the plan is free. There is no paid individual tier described, so developers can use the core plan without a recurring subscription.

Custom team services use custom pricing. They cover custom local configurations, cloud deployments and infrastructure support, making that option a fit for teams that need setup or ongoing help. The free plan remains the direct choice for individual use; the team offering is for services beyond that self-managed setup.

Platforms

Coasts supports macOS and Linux, including self-hosted environments. It requires Docker, Git, Node.js and socat. Linux installations use Docker Engine with the Compose plugin; canonical ports below 1024 may need additional host configuration before a checkout can bind to them. Developers whose projects rely on those ports should account for this host setup.

Who it's for

Coasts is best suited to developers who run multiple Git worktrees for one project and want each to have its own network, ports and services. It is particularly relevant to agentic coding workflows using one of the documented harnesses, as well as teams that want controlled sharing of databases, caches or volumes.

It is a less natural fit for developers seeking a hosted, turnkey environment or a setup without local prerequisites. Remote SSH runtimes can move services to another machine, but Coasts still depends on its local tooling requirements.

Pros and cons

Pros

• Isolation with selective sharing: separate networks and services help parallel worktrees coexist, while configurable resource sharing avoids duplicating everything.
• Broad local stack support: Docker Compose and non-containerized development setups are both supported.
• Local, open-source model: the project is free and MIT-licensed, with no hosted-service dependency or AI upsells.
• Remote hardware option: SSH runtimes can be combined with local environments for a hybrid setup.
• Host-managed secrets: credentials can be injected into containers without hardcoding them in a Coastfile.

Cons

• Several prerequisites: Docker, Git, Node.js and socat must be present, adding setup work before use.
• Linux port configuration: binding canonical ports below 1024 may require host changes.
• Sharing choices need care: developers must decide which services and volumes to share and which data to isolate.

Alternatives

For a broader comparison, see Container Development Environments. Colima is a free, MIT-licensed container runtime for macOS and Linux; choose it when container runtime support is the priority rather than Coasts' multi-worktree environments and resource-sharing controls.

Docker Desktop offers Docker Engine, Kubernetes, Docker Hub, Docker Scout and Docker Debug on a freemium plan. Its Personal plan costs nothing, billed monthly, while Pro costs $9 a month; it may suit readers looking for that broader Docker toolset. kind is a free, open-source tool for Linux, macOS, self-hosted setups and Windows, with no paid plans stated.

Kool offers a BYOC Free plan at no cost for one cluster, node, environment and app, with community support; its Managed Cloud Micro plan costs $5 a month. It is an alternative for readers considering a capped free tier or managed-cloud plan. Laravel Pint is a free, MIT-licensed PHP code style fixer, so it serves a different, code-formatting purpose.

Tilt is a free, open-source tool for Linux, macOS and Windows. Tokaido is a free, open-source option for Linux, macOS and Windows whose maker says its Docker containers can be forked and modified. Container Desktop is a free, MIT-licensed, open-source option for Linux, macOS and Windows.

Verdict

Choose Coasts if you regularly run several Git worktrees for one project and want isolated local environments with selective sharing, secret injection and the option to run services over SSH. Its free, MIT-licensed model makes that focused workflow accessible without a hosted service. Look elsewhere if you need a managed, ready-to-use environment or want to avoid installing and configuring its local prerequisites.