# jepsen-io/maelstrom

A workbench for writing toy implementations of distributed systems.

Repository: https://github.com/jepsen-io/maelstrom
Canonical: https://ross.abutalabs.com/products/maelstrom
Language: Clojure
License: EPL-1.0
License Family: copyleft
Topics: jepsen, distributed-systems, testing
Last push: 2026-07-10T12:13:06+00:00

## Health v2 (maintenance only)
Score: 64/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 91, release rhythm 8, longevity 100
- inputs: {"age_days": 3430, "days_push": 54, "days_rel": 637, "gap_med": null, "n_releases_24m": 1}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 3668, forks 214 (observed 2026-08-28T04:08:13.470040+00:00)

## What it is
Maelstrom is a workbench for learning distributed systems by writing toy implementations, built on the Jepsen testing library. It provides standardized workloads over a simple JSON STDIN/STDOUT protocol, a simulated network with latency and partition faults, and checkers that verify safety properties up to strict serializability.

## Use cases
- learn distributed systems by implementing toy servers
- test a broadcast or gossip protocol implementation
- verify a transactional key-value store for consistency anomalies
- simulate network partitions and message loss in a cluster
- practice building Raft or Paxos replicas
- run a distributed systems workshop exercise

## When to choose
- you want hands-on practice implementing distributed algorithms in any language
- you need fault injection and linearizability/serializability checking for a toy system
- you're following a distributed systems course or self-study curriculum

## When to avoid
- you need to test a real production distributed system rather than a toy
- you want a framework for building deployable distributed software
- you need non-simulated network testing on real infrastructure

## Facets
- artifact type: learning-resource
- maturity: active
- function: testing, e2e-testing, developer-tools
- domain: microservices, education, testing, developer-tools
- platform: jvm, cli
- tags: jepsen, distributed-systems, fault-injection, consistency-checking, workshop, json-protocol, network-simulation, linux, macos

## Member repositories
- jepsen-io/maelstrom (main) score 64

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:08:13.470040+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 2026-08-29T18:31:21.406835+00:00, confidence not recorded.
  - readme: https://github.com/jepsen-io/maelstrom (fetched 2026-08-28T04:08:13.470040+00:00, sha 975a44dcba09)
- Data as of 2026-08-30T08:39:29.467469+00:00.