# fmtlib/fmt

A modern formatting library

Repository: https://github.com/fmtlib/fmt
Canonical: https://ross.abutalabs.com/products/fmt
Homepage: https://fmt.dev
Language: C++
License: MIT
License Family: permissive
Topics: formatting, printf, output, chrono, performance, multiplatform, cross-platform, cpp, ranges, floating-point, unicode, c-plus-plus
Last push: 2026-08-23T16:31:29+00:00

## Health v2 (maintenance only)
Score: 92/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 99, release rhythm 77, longevity 100
- inputs: {"age_days": 5017, "days_push": 10, "days_rel": 78, "gap_med": 36.0, "n_releases_24m": 9}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 23765, forks 2959 (observed 2026-08-28T04:11:35.348574+00:00)

## What it is
{fmt} is a fast, safe C++ formatting library providing an alternative to C stdio and C++ iostreams, implementing C++20 std::format and C++23 std::print. It offers Python-like format string syntax, portable Unicode support, and high-performance floating-point and integer conversion.

## Use cases
- format strings in c++ faster than printf
- replace iostreams with a modern formatting api
- implement std::format on older c++ compilers
- format floating point numbers with correct rounding
- safe printf with positional arguments
- format dates and times with chrono
- format user-defined types in c++

## When to choose
- you need fast, type-safe text formatting in C++
- you want std::format/std::print on compilers lacking them
- you need portable Unicode-aware formatting across platforms

## When to avoid
- your project is C-only (use a C formatting library instead)
- you need locale-specific number formatting beyond positional arguments
- you are locked into iostream-based logging frameworks already

## Facets
- artifact type: library
- maturity: stable
- function: serialization, developer-tools
- domain: developer-tools, cross-platform, performance
- platform: cpp, cross-platform, windows
- tags: formatting, printf, iostreams, unicode, chrono, std-format, floating-point, linux, macos

## Member repositories
- fmtlib/fmt (main) score 92

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:11:35.348574+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 2026-08-29T16:56:20.941946+00:00, confidence not recorded.
  - readme: https://github.com/fmtlib/fmt (fetched 2026-08-28T04:11:35.348574+00:00, sha 2c19a9dd54ac)
  - homepage: https://fmt.dev (fetched 2026-08-29T07:53:57.408111+00:00, sha 1f5ada7b7977)
- Data as of 2026-08-30T08:39:29.467469+00:00.