# FStarLang/FStar

A Proof-oriented Programming Language

Repository: https://github.com/FStarLang/FStar
Canonical: https://ross.abutalabs.com/products/fstar
Homepage: https://fstar-lang.org
Language: F*
License: Apache-2.0
License Family: permissive
Topics: programming-language, verification, dependent-types, smt, theorem-proving, proof-assistant, ocaml, f-sharp, c-language, fstar, interactive-theorem-proving, dijkstra-monads, program-proof
Last push: 2026-08-26T21:40:07+00:00

## Health v2 (maintenance only)
Score: 99/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 99, longevity 100
- inputs: {"age_days": 4535, "days_push": 7, "days_rel": 10, "gap_med": 8, "n_releases_24m": 30}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 3100, forks 262 (observed 2026-08-28T04:07:43.509660+00:00)

## What it is
F* is a general-purpose proof-oriented programming language combining dependent types with SMT-based proof automation and interactive theorem proving. It verifies programs by default and can extract them to OCaml, F#, C, Wasm, or assembly via companion tools like KaRaMeL and Vale.

## Use cases
- formally verify program correctness
- prove security properties of cryptographic code
- write verified low-level C code via Low* and KaRaMeL
- learn dependent types and interactive theorem proving
- verify concurrent imperative programs with Pulse
- extract verified code to OCaml or F#

## When to choose
- you need machine-checked proofs of program correctness or security
- you want a dependently typed language with SMT-backed automation
- you are verifying cryptographic or low-level implementations like those in Project Everest

## When to avoid
- you just need a general-purpose language for ordinary application development without proofs
- your team has no background in formal methods or type theory
- you need fast iteration without a verification-oriented workflow

## Facets
- artifact type: cli-tool
- maturity: active
- function: programming-language, compiler, type-system, interpreter
- domain: programming-languages, compilers, security
- platform: windows, cross-platform, cli
- tags: proof-assistant, dependent-types, smt-solver, theorem-proving, program-verification, formal-methods, code-extraction, ocaml, f-sharp, karamel, algorithms, linux, macos

## Member repositories
- FStarLang/FStar (main) score 99

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:07:43.509660+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 2026-08-30T07:27:00.714852+00:00, confidence not recorded.
  - readme: https://github.com/FStarLang/FStar (fetched 2026-08-28T04:07:43.509660+00:00, sha bb6031f9bc5a)
  - homepage: https://fstar-lang.org (fetched 2026-08-29T09:42:15.003567+00:00, sha 736d996a3316)
- Data as of 2026-08-30T08:39:29.467469+00:00.