--- title: Device app development framework category: reference --- # Device app development framework Ledger maintains a set of repositories that, together, give you everything you need to **build**, **test**, **load**, and **submit** a Ledger device application. This page lists each tool, what it does, and when to reach for it. ## At a glance | Tool | What it gives you | Languages | OS support | | -------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------- | ------------ | ----------------------- | | [`app-boilerplate`](https://github.com/LedgerHQ/app-boilerplate) | Forkable C application skeleton | C | Linux / macOS / Windows | | [`app-boilerplate-rust`](https://github.com/LedgerHQ/app-boilerplate-rust) | Forkable Rust application skeleton | Rust | Linux / macOS / Windows | | [`app-plugin-boilerplate`](https://github.com/LedgerHQ/app-plugin-boilerplate) | Forkable Ethereum-app plugin skeleton | C | Linux / macOS / Windows | | [`ledger-dev-tools` VSCode extension](https://marketplace.visualstudio.com/items?itemName=LedgerHQ.ledger-dev-tools) | One-click build / test / load from the IDE | UI | Linux / macOS / Windows | | [`speculos`](https://github.com/LedgerHQ/speculos) | Emulator for Nano S+, Nano X, Stax, Flex, Nano Gen5 | Python (CLI) | Linux / macOS / WSL | | [`ragger`](https://github.com/LedgerHQ/ragger) | `pytest`-based functional test framework | Python | Linux / macOS / Windows | | [`ledger-app-workflows`](https://github.com/LedgerHQ/ledger-app-workflows) | Reusable GitHub Actions workflows | YAML | GitHub Actions | | [`ledger-app-builder`](https://github.com/LedgerHQ/ledger-app-builder) | Docker images with the toolchain pre-installed | Docker | Linux / macOS / Windows | ## When to pick which ### Starting a new app Fork **one of the boilerplates**: - `app-boilerplate`: new device app written in C. The most common starting point. Comes with C unit tests (cmocka), Ragger functional tests, CI workflows, and a `Makefile` already wired to the SDK. - `app-boilerplate-rust`: same scope as above, in Rust, for teams that prefer it. - `app-plugin-boilerplate`: only for **Ethereum-app plugins** (Clear Signing for an EVM contract). Different lifecycle: a plugin runs alongside the Ethereum app, not as a standalone app. ### Building locally Pick one of: - **VSCode + [`ledger-dev-tools`](https://marketplace.visualstudio.com/items?itemName=LedgerHQ.ledger-dev-tools)**: the recommended path on macOS and Windows. The extension launches the `ledger-app-dev-tools` Docker image behind the scenes and exposes Build / Run with Speculos / Run tests / Load on device as IDE tasks. - **Docker images from [`ledger-app-builder`](https://github.com/LedgerHQ/ledger-app-builder)**, in three flavours: - `ledger-app-builder-lite` (C only), - `ledger-app-builder` (default, C + Rust), - `ledger-app-dev-tools` (full image with Speculos and Ragger; what the VSCode extension uses). - **Bare host with the SDK directly**: works for advanced users on Linux who already have ARM toolchains; see the [SDK README](https://github.com/LedgerHQ/ledger-secure-sdk). For each device target you set the matching `BOLOS_SDK` variable: `$NANOX_SDK`, `$NANOSP_SDK`, `$STAX_SDK`, `$FLEX_SDK`, or `$APEX_SDK`. ### Running and emulating [`Speculos`](https://github.com/LedgerHQ/speculos) emulates Nano S+, Nano X, Stax,and Flex on a desktop computer; install with `pip install speculos` and run, for example: ```bash speculos --model nanosp build/nanos2/bin/app.elf ``` Caveats from the Speculos README to keep in mind: - It implements only the subset of syscalls common apps use (no app-install, firmware-update, or OS-info syscalls). - Memory-alignment behaviour differs from a real Nano S+ device. - The internal watchdog enforced on Nano X / Flex / Nano Gen5 / Stax is not emulated. ### Writing functional tests [`Ragger`](https://github.com/LedgerHQ/ragger) gives a single `pytest` interface that runs the same tests against three backends (Speculos, `LedgerComm`, and `LedgerWallet`), so you can switch between emulator and physical device with a flag: ```bash pytest # Speculos by default pytest --backend ledgerwallet # against a connected device ``` Install with `pip install 'ragger[all_backends]'`. The `app-boilerplate` repo ships an example suite you can copy. ### Continuous integration [`ledger-app-workflows`](https://github.com/LedgerHQ/ledger-app-workflows) provides reusable GitHub Actions workflows: - `guidelines_enforcer.yml`: checks your repo against Ledger's published app guidelines. Passing this workflow is a **mandatory** step to be listed on the Ledger app store. - Build-and-test workflows that build the app for every supported device and run the Ragger suite on Speculos. The boilerplates already wire these in. ## Putting it together A typical project layout uses these tools as follows: 1. Fork the right boilerplate (`app-boilerplate`, `app-boilerplate-rust`, or `app-plugin-boilerplate`). 2. Develop locally in VSCode with `ledger-dev-tools`, or directly with `ledger-app-builder` Docker images. 3. Run the app interactively in Speculos and write Ragger tests as features land. 4. Push to GitHub; the workflows from `ledger-app-workflows` build for every device, run the Ragger suite on Speculos, and run the guidelines enforcer. 5. When green, follow the [submission process](../submission-process/process) to ship the app through the Ledger Manager. ## See also - [Get started](../getting-started): set up a development environment and build your first app. - [Submission process](../submission-process/process): how an app reaches end users. - [Architecture](../explanation/architecture-diagram): where the device app fits in the wider system. - [Ledger Secure SDK](https://github.com/LedgerHQ/ledger-secure-sdk): the underlying SDK referenced by `BOLOS_SDK`.