---
id: clvm
version: "0.9.15"
license: https://opensource.org/licenses/Apache-2.0
license_treatment: permissive
maintenance: active
---

# clvm — [Contract Language | Chialisp] Virtual Machine

License: permissive · Maintenance: active · Downloads: 124.8K/mo

## What it is and what it does

clvm is a virtual machine implementation for Chialisp, a LISP-like smart contract language designed for the Chia blockchain. It interprets and executes Chialisp programs that define conditions for spending cryptocurrency—essentially a runtime for writing contracts that encumber and release funds based on cryptographic proofs and other conditions.

The package is in active development (Alpha status) and maintained by the Chia Network team. It depends on chia_rs for performance-critical operations and uses standard library compatibility shims (importlib_metadata, typing-extensions) for broad Python version support. It's positioned as a developer tool for blockchain engineers building on Chia, not a general-purpose language runtime.

Use it for:

- Building Chia blockchain smart contracts that define spending conditions and fund release logic
- Testing Chialisp programs locally before deployment to a live blockchain network
- Integrating Chia contract execution into Python-based wallet or node software
- Prototyping cryptocurrency payment schemes and escrow logic using Chialisp syntax

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

A LISP-like virtual machine for writing and executing smart contracts that control fund encumbrance and release on blockchain networks.

Yes, if you are developing on the Chia blockchain or need to execute Chialisp contracts in Python. The package is actively maintained, has no known vulnerabilities, and installs cleanly. However, it is in Alpha status, so expect API changes and verify production readiness for your use case before committing to it in critical systems.

## Install

pip install clvm
uv add clvm
poetry add clvm

## Installing clvm

Before you install: Low install friction with a pure-Python wheel distribution. The package is actively maintained with recent commits and supports current Python versions (3.8 through 3.11). Three runtime dependencies keep the dependency tree manageable.

License in practice: Apache 2.0 permissive license allows commercial and private use with minimal restrictions, making it suitable for production deployment in proprietary systems.

Quickstart:

pip install clvm

import clvm
# Use the virtual machine to execute Chialisp contracts
# See https://chialisp.com/ for language documentation

Requires Python 3.8.1 or later; depends on chia_rs which may require a Rust toolchain for compilation on some platforms.

Verify before relying:

- Whether chia_rs requires compilation from source on all platforms or if pre-built wheels are available
- Performance characteristics and typical execution speed for contract evaluation
- Maturity level beyond 'Alpha' status and production readiness guarantees

## Package facts

- License: https://opensource.org/licenses/Apache-2.0 (permissive)
- Python support: supports_current
- Install friction: low
- Maintenance: active
- Downloads: 124.8K/month (top 15,000 on PyPI)
- Known vulnerabilities: none known

## Tags

lisp virtual machine, smart contract language, blockchain scripting, chialisp interpreter, fund encumbrance, contract execution engine, cryptocurrency smart contracts, blockchain, smart-contracts, chia-network

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