1# Developing Extensions
  2
  3## Extension Capabilities
  4
  5Extensions can add the following capabilities to Zed:
  6
  7- [Languages](./languages.md)
  8- [Debuggers](./debugger-extensions.md)
  9- [Themes](./themes.md)
 10- [Icon Themes](./icon-themes.md)
 11- [Slash Commands](./slash-commands.md)
 12- [MCP Servers](./mcp-extensions.md)
 13
 14## Developing an Extension Locally
 15
 16Before starting to develop an extension for Zed, be sure to [install Rust via rustup](https://www.rust-lang.org/tools/install).
 17
 18> Rust must be installed via rustup. If you have Rust installed via homebrew or otherwise, installing dev extensions will not work.
 19
 20When developing an extension, you can use it in Zed without needing to publish it by installing it as a _dev extension_.
 21
 22From the extensions page, click the `Install Dev Extension` button (or the {#action zed::InstallDevExtension} action) and select the directory containing your extension.
 23
 24If you need to troubleshoot, you can check the Zed.log ({#action zed::OpenLog}) for additional output. For debug output, close and relaunch zed with the `zed --foreground` from the command line which show more verbose INFO level logging.
 25
 26If you already have the published version of the extension installed, the published version will be uninstalled prior to the installation of the dev extension. After successful installation, the `Extensions` page will indicate that the upstream extension is "Overridden by dev extension".
 27
 28## Directory Structure of a Zed Extension
 29
 30A Zed extension is a Git repository that contains an `extension.toml`. This file must contain some
 31basic information about the extension:
 32
 33```toml
 34id = "my-extension"
 35name = "My extension"
 36version = "0.0.1"
 37schema_version = 1
 38authors = ["Your Name <you@example.com>"]
 39description = "My cool extension"
 40repository = "https://github.com/your-name/my-zed-extension"
 41```
 42
 43In addition to this, there are several other optional files and directories that can be used to add functionality to a Zed extension. An example directory structure of an extension that provides all capabilities is as follows:
 44
 45```
 46my-extension/
 47  extension.toml
 48  Cargo.toml
 49  src/
 50    lib.rs
 51  languages/
 52    my-language/
 53      config.toml
 54      highlights.scm
 55  themes/
 56    my-theme.json
 57```
 58
 59## WebAssembly
 60
 61Procedural parts of extensions are written in Rust and compiled to WebAssembly. To develop an extension that includes custom code, include a `Cargo.toml` like this:
 62
 63```toml
 64[package]
 65name = "my-extension"
 66version = "0.0.1"
 67edition = "2021"
 68
 69[lib]
 70crate-type = ["cdylib"]
 71
 72[dependencies]
 73zed_extension_api = "0.1.0"
 74```
 75
 76Use the latest version of the [`zed_extension_api`](https://crates.io/crates/zed_extension_api) available on crates.io. Make sure it's still [compatible with Zed versions](https://github.com/zed-industries/zed/blob/main/crates/extension_api#compatible-zed-versions) you want to support.
 77
 78In the `src/lib.rs` file in your Rust crate you will need to define a struct for your extension and implement the `Extension` trait, as well as use the `register_extension!` macro to register your extension:
 79
 80```rs
 81use zed_extension_api as zed;
 82
 83struct MyExtension {
 84    // ... state
 85}
 86
 87impl zed::Extension for MyExtension {
 88    // ...
 89}
 90
 91zed::register_extension!(MyExtension);
 92```
 93
 94> `stdout`/`stderr` is forwarded directly to the Zed process. In order to see `println!`/`dbg!` output from your extension, you can start Zed in your terminal with a `--foreground` flag.
 95
 96## Forking and cloning the repo
 97
 981. Fork the repo
 99
100> Note: It is very helpful if you fork the `zed-industries/extensions` repo to a personal GitHub account instead of a GitHub organization, as this allows Zed staff to push any needed changes to your PR to expedite the publishing process.
101
1022. Clone the repo to your local machine
103
104```sh
105# Substitute the url of your fork here:
106# git clone https://github.com/zed-industries/extensions
107cd extensions
108git submodule init
109git submodule update
110```
111
112## Extension License Requirements
113
114As of October 1st, 2025, extension repositories must include a license.
115The following licenses are accepted:
116
117- [Apache 2.0](https://www.apache.org/licenses/LICENSE-2.0)
118- [BSD 3-Clause](https://opensource.org/license/bsd-3-clause)
119- [GNU GPLv3](https://www.gnu.org/licenses/gpl-3.0.en.html)
120- [MIT](https://opensource.org/license/mit)
121
122This allows us to distribute the resulting binary produced from your extension code to our users.
123Without a valid license, the pull request to add or update your extension in the following steps will fail CI.
124
125Your license file should be at the root of your extension repository. Any filename that has `LICENCE` or `LICENSE` as a prefix (case insensitive) will be inspected to ensure it matches one of the accepted licenses. See the [license validation source code](https://github.com/zed-industries/extensions/blob/main/src/lib/license.js).
126
127> This license requirement applies only to your extension code itself (the code that gets compiled into the extension binary).
128> It does not apply to any tools your extension may download or interact with, such as language servers or other external dependencies.
129> If your repository contains both extension code and other projects (like a language server), you are not required to relicense those other projects—only the extension code needs to be one of the aforementioned accepted licenses.
130
131## Publishing your extension
132
133To publish an extension, open a PR to [the `zed-industries/extensions` repo](https://github.com/zed-industries/extensions).
134
135In your PR, do the following:
136
1371. Add your extension as a Git submodule within the `extensions/` directory
138
139```sh
140git submodule add https://github.com/your-username/foobar-zed.git extensions/foobar
141git add extensions/foobar
142```
143
144> All extension submodules must use HTTPS URLs and not SSH URLS (`git@github.com`).
145
1462. Add a new entry to the top-level `extensions.toml` file containing your extension:
147
148```toml
149[my-extension]
150submodule = "extensions/my-extension"
151version = "0.0.1"
152```
153
154> If your extension is in a subdirectory within the submodule you can use the `path` field to point to where the extension resides.
155
1563. Run `pnpm sort-extensions` to ensure `extensions.toml` and `.gitmodules` are sorted
157
158Once your PR is merged, the extension will be packaged and published to the Zed extension registry.
159
160> Extension IDs and names should not contain `zed` or `Zed`, since they are all Zed extensions.
161
162## Updating an extension
163
164To update an extension, open a PR to [the `zed-industries/extensions` repo](https://github.com/zed-industries/extensions).
165
166In your PR do the following:
167
1681. Update the extension's submodule to the commit of the new version.
1692. Update the `version` field for the extension in `extensions.toml`
170   - Make sure the `version` matches the one set in `extension.toml` at the particular commit.
171
172If you'd like to automate this process, there is a [community GitHub Action](https://github.com/huacnlee/zed-extension-action) you can use.
173
174> **Note:** If your extension repository has a different license, you'll need to update it to be one of the [accepted extension licenses](#extension-license-requirements) before publishing your update.