# jamesmunns/postcard

A no_std + serde compatible message library for Rust

Repository: https://github.com/jamesmunns/postcard
Canonical: https://ross.abutalabs.com/products/postcard
Language: Rust
License: Apache-2.0
License Family: permissive
Last push: 2026-07-20T20:45:07+00:00

## Health v2 (maintenance only)
Score: 77/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 93, release rhythm 44, longevity 100
- inputs: {"age_days": 2709, "days_push": 44, "days_rel": 375, "gap_med": 3.5, "n_releases_24m": 13}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1494, forks 141 (observed 2026-08-28T04:04:53.026151+00:00)

## What it is
Postcard is a no_std-focused serializer and deserializer for Serde in Rust, designed for embedded and other constrained environments. It provides a stable, documented wire format with varint encoding and supports heapless and alloc-based serialization.

## Use cases
- serialize messages on a microcontroller with no_std
- use serde in embedded Rust firmware
- exchange data between MCU and desktop over serial
- compact binary encoding of Rust structs
- drop-in serde format replacement for constrained devices

## When to choose
- writing embedded Rust with no_std and serde
- needing a compact, stable binary wire format
- communicating between microcontroller and host with the same code

## When to avoid
- needing human-readable formats like JSON
- building non-Rust systems without serde support

## Facets
- artifact type: library
- maturity: stable
- function: serialization, embedded
- domain: embedded-systems, developer-tools
- platform: embedded, rust, cross-platform
- tags: no-std, serde, wire-format, varint, cobs, framing, microcontroller

## Member repositories
- jamesmunns/postcard (main) score 77

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:04:53.026151+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T04:33:22.402448+00:00, confidence not recorded.
  - readme: https://github.com/jamesmunns/postcard (fetched 2026-08-28T04:04:53.026151+00:00, sha a08827c37f61)
  - registry_crates: https://crates.io/api/v1/crates/postcard (fetched 2026-08-29T11:38:48.451337+00:00, sha 026eaf6c19da)
- Data as of 2026-08-30T08:39:29.467469+00:00.