---
id: rlp
version: "4.1.0"
license: MIT
license_treatment: permissive
maintenance: active
---

# rlp — rlp: A package for Recursive Length Prefix encoding and decoding

License: permissive · Maintenance: active · Downloads: 6.0M/mo

## What it is and what it does

RLP is a serialization format that encodes nested byte arrays into a single byte string, widely used in Ethereum for encoding transactions, blocks, and other data structures. This package provides Python functions to encode Python data structures (lists, bytes) into RLP format and decode RLP-encoded bytes back into their original form.

The package is straightforward: you pass it data to encode or RLP bytes to decode, and it handles the serialization logic. It depends only on eth-utils, making it lightweight and suitable for integration into blockchain tools, Ethereum clients, or any system that needs to work with RLP-serialized data.

Use it for:

- Encode transaction data for Ethereum network communication or storage
- Decode RLP-serialized blockchain data received from peers or APIs
- Serialize complex nested structures in blockchain applications
- Build Ethereum-compatible tools that need standard data encoding
- Test blockchain protocol implementations that rely on RLP format

## Worth the install?

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

Encodes and decodes data using Recursive Length Prefix (RLP), a serialization format commonly used in Ethereum and blockchain systems.

Yes. It is actively maintained, has no known vulnerabilities, carries a permissive MIT license, and installs with minimal friction. Install it if you work with Ethereum, blockchain systems, or need RLP serialization; skip it if you have no use for that specific encoding format.

## Install

pip install rlp
uv add rlp
poetry add rlp

## Installing rlp

Before you install: Low friction installation with a pure Python wheel. Actively maintained as of 2026-07-16 with a single lightweight runtime dependency (eth-utils).

License in practice: MIT license permits use, modification, and distribution with minimal restrictions, making it suitable for both open-source and proprietary projects.

Quickstart:

pip install rlp

import rlp
encoded = rlp.encode([b'hello', b'world'])
decoded = rlp.decode(encoded)

Verify before relying:

- Whether the package handles edge cases like deeply nested structures or very large payloads
- Performance characteristics compared to alternative RLP implementations
- Completeness of RLP specification coverage beyond basic encode/decode

## Package facts

- License: MIT (permissive)
- Python support: supports_current
- Install friction: low
- Maintenance: active
- Downloads: 6.0M/month (top 5,000 on PyPI)
- Known vulnerabilities: none known

## Tags

rlp encoding decoding, recursive length prefix, ethereum serialization, blockchain data encoding, rlp python library, data serialization format, ethereum rlp codec, ethereum, serialization, blockchain

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