# Tessil/robin-map

C++ implementation of a fast hash map and hash set using robin hood hashing

Repository: https://github.com/Tessil/robin-map
Canonical: https://ross.abutalabs.com/products/robin-map
Language: C++
License: MIT
License Family: permissive
Topics: c-plus-plus, cpp, hash-map, data-structures, header-only, hash-table
Last push: 2026-06-13T09:27:46+00:00

## Health v2 (maintenance only)
Score: 67/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 87, release rhythm 22, longevity 100
- inputs: {"age_days": 3310, "days_push": 81, "days_rel": 304, "gap_med": 217, "n_releases_24m": 2}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1503, forks 146 (observed 2026-08-28T04:04:54.542759+00:00)

## What it is
robin-map is a header-only C++ library providing fast hash map and hash set containers (tsl::robin_map, tsl::robin_set, plus prime-growth variants) built on open addressing with robin hood hashing and backward shift deletion. It serves as a high-performance alternative to std::unordered_map, with heterogeneous lookup, move-only key support, optional stored hashes, and serialization support.

## Use cases
- fast hash map in C++
- faster alternative to std::unordered_map
- header-only hash set library
- robin hood hashing implementation
- C++ hash table with heterogeneous lookup for pointer-like keys
- hash map that tolerates a poor hash function
- hash map supporting move-only non-default-constructible keys

## When to choose
- std::unordered_map is a profiling bottleneck and you need a faster in-memory hash map or set
- You want a zero-build header-only container that drops into any C++ project or CMake build
- You need heterogeneous find, move-only keys, stored-hash lookups, or efficient container serialization

## When to avoid
- You need an ordered or sorted associative container with stable iteration order
- You need a concurrent, thread-safe hash table for shared use across threads
- You need a persistent or disk-backed key-value store rather than an in-memory container

## Facets
- artifact type: library
- maturity: stable
- function: serialization, developer-tools
- domain: developer-tools
- platform: cpp, cross-platform
- tags: hash-map, hash-set, hash-table, data-structures, robin-hood-hashing, open-addressing, header-only, containers, std-unordered_map-alternative, cmake, algorithms

## Member repositories
- Tessil/robin-map (main) score 67

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:04:54.542759+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 2026-08-30T04:32:47.375415+00:00, confidence not recorded.
  - readme: https://github.com/Tessil/robin-map (fetched 2026-08-28T04:04:54.542759+00:00, sha 53f17dada23f)
- Data as of 2026-08-30T08:39:29.467469+00:00.