# ulfjack/ryu

Converts floating point numbers to decimal strings

Repository: https://github.com/ulfjack/ryu
Canonical: https://ross.abutalabs.com/products/ulfjack-ryu
Language: C++
License: Apache-2.0
License Family: permissive
Last push: 2026-02-09T23:30:21+00:00

## Health v2 (maintenance only)
Score: 62/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 66, release rhythm 35, longevity 100
- inputs: {"age_days": 3122, "days_push": 205, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1347, forks 111 (observed 2026-08-28T04:04:27.584860+00:00)

## What it is
Ryu is a C library (with a Java port) for converting IEEE-754 floating-point numbers to decimal strings using shortest, fixed, and scientific formats. Its algorithms are peer-reviewed and the fastest known for float-to-string conversion, guaranteeing round-trip safety.

## Use cases
- convert floats to shortest decimal strings
- fast alternative to sprintf for float formatting
- round-trip safe float serialization
- format doubles in scientific or fixed notation
- convert half/float/double/long double/float128 to strings

## When to choose
- you need the fastest float-to-string conversion
- you need shortest round-trip-safe decimal output
- you need to support multiple IEEE widths including 128-bit

## When to avoid
- you need string-to-float parsing
- you need locale-aware formatting
- you need 128-bit fixed or scientific output

## Facets
- artifact type: library
- maturity: stable
- function: serialization, parser
- domain: developer-tools, performance
- platform: cpp, c, cross-platform, jvm
- tags: floating-point, number-formatting, round-trip, float-to-string, ieee-754, algorithms

## Member repositories
- ulfjack/ryu (main) score 62

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:04:27.584860+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 2026-08-30T04:42:38.747112+00:00, confidence not recorded.
  - readme: https://github.com/ulfjack/ryu (fetched 2026-08-28T04:04:27.584860+00:00, sha 740ae9e965d3)
- Data as of 2026-08-30T08:39:29.467469+00:00.