---
id: imgtool
version: "2.4.0"
license: Apache Software License
license_treatment: permissive
maintenance: active
---

# imgtool — MCUboot's image signing and key management

License: permissive · Maintenance: active · Downloads: 846.6K/mo

## What it is and what it does

imgtool is the image signing and key management utility for MCUboot, a secure bootloader for 32-bit microcontrollers. It handles the cryptographic signing of firmware images so that MCUboot can verify their authenticity before booting them on target hardware. The package is part of the MCUboot project, which provides a common bootloader infrastructure across multiple embedded operating systems and SoCs.

The tool relies on five runtime dependencies: cbor2, click, cryptography, intelhex, and pyyaml. It is actively maintained with no known security vulnerabilities and supports current Python versions. The project has a stable release cadence and is used in embedded systems development.

Use it for:

- Sign firmware binaries before deployment to ensure MCUboot can authenticate them during boot.
- Manage and rotate cryptographic keys used for firmware image validation across device fleets.
- Integrate firmware signing into embedded CI/CD pipelines for automated secure builds.
- Generate signed firmware images compatible with MCUboot on supported platforms.
- Validate firmware integrity and authenticity in over-the-air update workflows.

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

imgtool signs and manages cryptographic keys for MCUboot firmware images, enabling secure bootloader validation on microcontrollers.

Yes. imgtool is a focused, actively maintained utility with low install friction and no known vulnerabilities. Install it if you are working with MCUboot or need to sign firmware images for microcontroller bootloaders. The Apache Software License poses no barrier to commercial use.

## Install

pip install imgtool
uv add imgtool
poetry add imgtool

## Installing imgtool

Before you install: Low install friction with a pure-Python wheel and five runtime dependencies. The project is actively maintained with recent commits and steady releases since first release in 2018.

License in practice: Apache Software License is permissive, allowing commercial and private use with minimal restrictions; you must retain license and copyright notices in distributions.

Quickstart:

pip install imgtool

from imgtool import main
main(['sign', '--key', 'key.pem', '--version', 'X.Y', 'input.bin', 'output.bin'])

Requires a cryptographic key file and input firmware binary; Python 3.6 or later (requires_python: >=3.6).

Verify before relying:

- Whether the package provides a command-line interface or is intended primarily as a library.
- What key formats and signing algorithms are supported beyond what the fact sheet indicates.
- Whether hardware-specific MCUboot ports require additional setup beyond imgtool itself.
- Specific usage patterns and API surface for programmatic key management.

## Package facts

- License: Apache Software License (permissive)
- Python support: supports_current
- Install friction: low
- Maintenance: active
- Downloads: 846.6K/month (top 5,000 on PyPI)
- Known vulnerabilities: none known

## Tags

firmware image signing tool, microcontroller bootloader image, secure firmware signing, MCUboot image tool, embedded device firmware signing, cryptographic key management embedded, bootloader image validation, embedded-systems, firmware-signing, bootloader

[View on SkillFed](https://skillfed.io/packages/imgtool) · [View on PyPI](https://pypi.org/project/imgtool/)