MCUboot is a secure bootloader for 32-bit microcontrollers, providing signed and encrypted firmware upgrade capabilities. The repository contains the core bootloader library (C) with support for multiple RTOS platforms (Zephyr, Mynewt, NuttX, Mbed OS, Espressif, Cypress), a Python image signing and management tool (imgtool), a Rust-based simulator for testing boot scenarios, and vendored cryptographic libraries (TinyCrypt, Mbed TLS subset, fiat-crypto). The system architecture is a library with platform-specific ports: the common boot logic (bootutil) handles image validation, swap algorithms (scratch, move, offset, direct-XIP, RAM-load), encryption, and fault-injection hardening. Each platform provides flash map, logging, watchdog, and boot entry point implementations. The codebase is highly configurable via compile-time flags, supporting multiple signature schemes (RSA, ECDSA, Ed25519), encryption backends, and upgrade modes. It is not a standalone application but a bootloader intended to be integrated into embedded firmware projects.