# karpathy/cryptos

Pure Python from-scratch zero-dependency implementation of Bitcoin for educational purposes

Repository: https://github.com/karpathy/cryptos
Canonical: https://ross.abutalabs.com/products/cryptos
Language: Jupyter Notebook
License Family: other
Topics: bitcoin, cryptocurrency, crypto, elliptic-curves
Last push: 2021-06-21T04:53:12+00:00

## Health v2 (maintenance only)
Score: 32/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 0, release rhythm 35, longevity 100
- inputs: {"age_days": 1957, "days_push": 1899, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases, no_license
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1926, forks 328 (observed 2026-08-28T04:05:55.561410+00:00)

## What it is
A pure Python, zero-dependency from-scratch implementation of Bitcoin, including SHA-256, elliptic curve math, ECDSA signatures, key/address generation, and transaction parsing. It is written as an educational resource (with Jupyter notebooks) and is explicitly not intended for production use.

## Use cases
- learn how bitcoin works under the hood
- understand sha-256 step by step
- study elliptic curve cryptography and ecdsa
- parse raw bitcoin transactions in python
- generate bitcoin key pairs and addresses from scratch
- teach a course on cryptocurrency internals

## When to choose
- you want to learn or teach bitcoin and crypto primitives from first principles
- you need readable, dependency-free reference implementations of sha-256, elliptic curves, or ecdsa
- you want to experiment with bitcoin transaction structures in pure python

## When to avoid
- you need a fast, secure, production-ready bitcoin library
- you want to handle real funds or mainnet transactions
- you need audited cryptographic code

## Facets
- artifact type: learning-resource
- maturity: maintenance
- function: cryptography, serialization, cli, parser
- domain: education
- platform: python, cli, cross-platform
- tags: bitcoin, elliptic-curves, sha256, ecdsa, educational, zero-dependency, jupyter-notebook, cryptocurrency, algorithms

## Member repositories
- karpathy/cryptos (main) score 32

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:05:55.561410+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 2026-08-30T03:09:13.542653+00:00, confidence not recorded.
  - readme: https://github.com/karpathy/cryptos (fetched 2026-08-28T04:05:55.561410+00:00, sha 0d10c076e0a6)
- Data as of 2026-08-30T08:39:29.467469+00:00.