# [devenv.sh](https://devenv.sh) - Fast, Declarative, Reproducible, and Composable Developer Environments
[](https://devenv.sh)
[](https://builtwithnix.org)
[](https://discord.gg/naMgvexb6q)
[](https://github.com/cachix/devenv/releases)
[](https://github.com/cachix/devenv/actions/workflows/release.yml?branch=main)
## Features
### Developer experience
- **[Terminal UI](https://devenv.sh/blog/2026/03/05/devenv-20-a-fresh-interface-to-nix/#terminal-ui)** with live build progress, task hierarchy, and error details
- **[Native shell reloading](https://devenv.sh/blog/2026/03/05/devenv-20-a-fresh-interface-to-nix/#native-shell-reloading)** that rebuilds in the background while your shell stays interactive
- **[Instant environments](https://devenv.sh/blog/2024/10/03/devenv-13-instant-developer-environments-with-nix-caching/)** with incremental Nix evaluation caching (sub 100ms when nothing changed)
- **[LSP for devenv.nix](https://devenv.sh/lsp/)** with autocomplete, hover docs, and go to definition via bundled nixd
- **[Ad hoc environments](https://devenv.sh/ad-hoc-developer-environments/)** from the CLI without any config files (`--option languages.rust.enable:bool true`)
- **[Out of tree devenvs](https://devenv.sh/ad-hoc-developer-environments/)** to use configs from other repos (`--from github:myorg/configs`)
### Languages, packages, and services
- **[50+ languages](https://devenv.sh/languages/)** with built in tooling: compilers, LSP servers, formatters, linters, and version selection
- **[100,000+ packages](https://devenv.sh/packages/)** from Nixpkgs for Linux, macOS, x64, and ARM64 (including WSL2)
- **[40+ services](https://devenv.sh/services/)** like PostgreSQL, Redis, MySQL, MongoDB, Elasticsearch, Caddy, and more
### Processes and tasks
- **[Native process manager](https://devenv.sh/processes/)** written in Rust with dependency ordering, restart policies, readiness probes (exec, HTTP, systemd notify), socket activation, watchdog heartbeats, and file watching
- **[Automatic port allocation](https://devenv.sh/processes/#automatic-port-allocation)** that finds free ports so parallel environments never collide
- **[Tasks](https://devenv.sh/tasks/)** with DAG based execution, caching, parallel runs, and namespace support
- **[Scripts](https://devenv.sh/scripts/)** with access to all environment packages
### Packaging and deployment
- **[OCI containers](https://devenv.sh/containers/)** built from your environment without Docker
- **[Outputs](https://devenv.sh/outputs/)** for packaging apps using each language's best tools (crate2nix, uv2nix, ...)
- **[Polyrepo support](https://devenv.sh/guides/polyrepo/)** to reference outputs and options across repositories
### Composition and configuration
- **[Profiles](https://devenv.sh/profiles/)** for environment variants (`--profile backend --profile testing`)
- **[Composable via imports](https://devenv.sh/composing-using-imports/)** to share and reuse environments across projects
- **[Inputs](https://devenv.sh/inputs/)** for pinning and overriding Nix dependencies
### Security and integrations
- **[SecretSpec](https://devenv.sh/integrations/secretspec/)** for declarative, provider agnostic secrets management (keyring, 1Password, dotenv)
- **[Git hooks](https://devenv.sh/git-hooks/)** via git-hooks.nix with pre configured formatters and linters
- **[Testing](https://devenv.sh/tests/)** with `devenv test` that automatically starts and stops processes
- **[direnv integration](https://devenv.sh/integrations/direnv/)** for automatic shell activation when entering a directory
- **[MCP server](https://devenv.sh/mcp/)** for AI assistant integration (package and option search)
- **[AI generation](https://devenv.new)** to scaffold environments from a natural language description
## Quick start
Running ``devenv init`` generates ``devenv.nix``:
```nix
{ pkgs, lib, config, inputs, ... }:
{
# https://devenv.sh/basics/
env.GREET = "devenv";
# https://devenv.sh/packages/
packages = [ pkgs.git ];
# https://devenv.sh/languages/
# languages.rust.enable = true;
# https://devenv.sh/processes/
# processes.dev.exec = "${lib.getExe pkgs.watchexec} -n -- ls -la";
# https://devenv.sh/services/
# services.postgres.enable = true;
# https://devenv.sh/scripts/
scripts.hello.exec = ''
echo hello from $GREET
'';
# https://devenv.sh/basics/
enterShell = ''
hello # Run scripts directly
git --version # Use packages
'';
# https://devenv.sh/tasks/
# tasks = {
# "myproj:setup".exec = "mytool build";
# "devenv:enterShell".after = [ "myproj:setup" ];
# };
# https://devenv.sh/tests/
enterTest = ''
echo "Running tests"
git --version | grep --color=auto "${pkgs.git.version}"
'';
# https://devenv.sh/outputs/
# outputs = {
# rust-app = config.languages.rust.import ./rust-app {};
# python-app = config.languages.python.import ./python-app {};
# };
# https://devenv.sh/git-hooks/
# git-hooks.hooks.shellcheck.enable = true;
# See full reference at https://devenv.sh/reference/options/
}
```
And ``devenv shell`` activates the environment.
## Commands
```
$ devenv
https://devenv.sh 2.0.0: Fast, Declarative, Reproducible, and Composable Developer Environments
Usage: devenv [OPTIONS] [COMMAND]
Commands:
init Scaffold devenv.yaml, devenv.nix, and .gitignore.
generate Generate devenv.yaml and devenv.nix using AI
shell Activate the developer environment. https://devenv.sh/basics/
update Update devenv.lock from devenv.yaml inputs. http://devenv.sh/inputs/
search Search for packages and options in nixpkgs. https://devenv.sh/packages/#searching-for-a-file
info Print information about this developer environment.
up Start processes in the foreground. https://devenv.sh/processes/
processes Start or stop processes. https://devenv.sh/processes/
tasks Run tasks. https://devenv.sh/tasks/
test Run tests. http://devenv.sh/tests/
container Build, copy, or run a container. https://devenv.sh/containers/
inputs Add an input to devenv.yaml. https://devenv.sh/inputs/
changelogs Show relevant changelogs.
repl Launch an interactive environment for inspecting the devenv configuration.
gc Delete previous shell generations. See https://devenv.sh/garbage-collection
build Build any attribute in devenv.nix.
eval Evaluate any attribute in devenv.nix and return JSON.
direnvrc Print a direnvrc that adds devenv support to direnv. See https://devenv.sh/integrations/direnv/.
version Print the version of devenv.
mcp Launch Model Context Protocol server for AI assistants
lsp Start the nixd language server for devenv.nix.
help Print this message or the help of the given subcommand(s)
Input overrides:
--from
Source for devenv.nix.
Can be either a filesystem path (with path: prefix) or a flake input reference.
Examples:
--from github:cachix/devenv
--from github:cachix/devenv?dir=examples/simple
--from path:/absolute/path/to/project
--from path:./relative/path
-o, --override-input
Override inputs in devenv.yaml.
Examples:
--override-input nixpkgs github:NixOS/nixpkgs/nixos-unstable
--override-input nixpkgs path:/path/to/local/nixpkgs
-O, --option
Override configuration options with typed values.
OPTION must include a type: :
Supported types: string, int, float, bool, path, pkg, pkgs
List types (pkgs) append to existing values by default.
Add a ! suffix to replace instead: pkgs!
Examples:
--option languages.rust.channel:string beta
--option services.postgres.enable:bool true
--option languages.python.version:string 3.10
--option packages:pkgs "ncdu git" (appends to packages)
--option packages:pkgs! "ncdu git" (replaces all packages)
Nix options:
-j, --max-jobs
Maximum number of Nix builds to run concurrently.
Defaults to 1/4 of available CPU cores (minimum 1).
[env: DEVENV_MAX_JOBS=]
-u, --cores
Number of CPU cores available to each build.
Defaults to available cores divided by max-jobs (minimum 1).
[env: DEVENV_CORES=]
-s, --system
Override the target system.
Defaults to the host system (e.g. aarch64-darwin, x86_64-linux).
-i, --impure
Relax the hermeticity of the environment.
--no-impure
Force a hermetic environment, overriding config.
--offline
Disable substituters and consider all previously downloaded files up-to-date.
--nix-option
Pass additional options to nix commands.
These options are passed directly to Nix using the --option flag.
See `man nix.conf` for the full list of available options.
Examples:
--nix-option sandbox false
--nix-option keep-outputs true
--nix-option system x86_64-darwin
--nix-debugger
Enter the Nix debugger on failure.
Shell options:
-c, --clean [...]
Ignore existing environment variables when entering the shell. Pass a list of comma-separated environment variables to let through.
-P, --profile
Activate one or more profiles defined in devenv.nix.
Profiles allow you to define different configurations that can be merged with your base configuration.
See https://devenv.sh/profiles for more information.
Examples:
--profile python-3.14
--profile backend --profile fast-startup
--reload
Enable auto-reload when config files change (default).
--no-reload
Disable auto-reload when config files change.
Cache options:
--eval-cache
Enable caching of Nix evaluation results (default).
--no-eval-cache
Disable caching of Nix evaluation results.
--refresh-eval-cache
Force a refresh of the Nix evaluation cache.
--refresh-task-cache
Force a refresh of the task cache.
Secretspec options:
--secretspec-provider
Override the secretspec provider
[env: SECRETSPEC_PROVIDER=]
--secretspec-profile
Override the secretspec profile
[env: SECRETSPEC_PROFILE=]
Tracing options:
--trace-output
Enable tracing and set the output destination: stdout, stderr, or file:. Tracing is disabled by default.
[env: DEVENV_TRACE_OUTPUT=]
--trace-format
Set the trace output format. Only takes effect when tracing is enabled via --trace-output.
Possible values:
- full: A verbose structured log format used for debugging
- json: A JSON log format used for machine consumption
- pretty: A pretty human-readable log format used for debugging
[env: DEVENV_TRACE_FORMAT=]
[default: json]
Global options:
-v, --verbose
Enable additional debug logs.
-q, --quiet
Silence all logs
--tui
Enable the interactive terminal interface (default when interactive).
[env: DEVENV_TUI=]
--no-tui
Disable the interactive terminal interface.
-h, --help
Print help (see a summary with '-h')
-V, --version
Print version information and exit
```
## Documentation
- [Getting Started](https://devenv.sh/getting-started/)
- [Basics](https://devenv.sh/basics/)
- [Roadmap](https://devenv.sh/roadmap/)
- [Blog](https://devenv.sh/blog/)
- [`devenv.yaml` reference](https://devenv.sh/reference/yaml-options/)
- [`devenv.nix` reference](https://devenv.sh/reference/options/)
- [Contributing](https://devenv.sh/community/contributing/)
