substrate-interface
Library for interfacing with a Substrate node
Decision gist · record as of 2026-08-14
Yes. Active maintenance, no known vulnerabilities, permissive license, and low install friction make this a solid choice for Substrate blockchain development. The 16 dependencies are well-established cryptographic and networking libraries. Install if you need to interact with Polkadot, Kusama, or other Substrate chains from Python.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Requires a running Substrate node RPC endpoint (local or remote) or uses embedded light client via smoldot-light; WebSocket connectivity needed.
- Low friction installation with a pure-Python wheel.
- Actively maintained with recent commits and no known vulnerabilities.
License · maintenance · safety
permissive license (permissive) — Licensed under Apache Software License (permissive), allowing commercial and private use with minimal restrictions.
last release 2026-01-20 (206 days) · last repo commit 2026-06-15 · 256 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 261,738 downloads/mo, #8,382 on PyPI
Alternatives
Verify before relying
pip install substrate-interface
from substrate_interface import SubstrateInterface
substrate = SubstrateInterface(url="ws://127.0.0.1:9944")
result = substrate.query('System', 'Account', ['F4xQKRUagnSGjFqafyhajLs94e7Vvzvr8ebwYJceKpr8R7T'])
print(result.value['data']['free'])- Performance characteristics when querying large datasets or high-frequency RPC calls
- Compatibility scope with runtimes older than MetadataV14 or under active development
What it is and what it does
substrate-interface is a Python client library for interacting with Substrate-based blockchains like Polkadot and Kusama. It provides methods to query on-chain storage, compose and sign transactions (extrinsics), and handle the SCALE codec used by Substrate runtimes. The library can connect either to a remote node via WebSocket RPC or use an embedded light client.
The package wraps low-level blockchain operations into higher-level Python abstractions, automatically discovering runtime metadata and chain properties from the connected node. It handles cryptographic signing via keypairs, manages account balances and state queries, and abstracts away the complexity of SCALE encoding for common operations. With 16 runtime dependencies including cryptographic libraries (ecdsa, PyNaCl, pycryptodome) and codec tools (scalecodec, xxhash), it provides a complete toolkit for Substrate development.
Use it for
- Query account balances and storage state from a Polkadot or Kusama node
- Compose and submit signed transactions (extrinsics) to transfer funds or call runtime functions
- Build automation scripts that interact with Substrate-based chains programmatically
- Decode and encode SCALE-formatted data for custom runtime interactions
- Monitor on-chain events and state changes via RPC subscriptions
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes.
Active maintenance, no known vulnerabilities, permissive license, and low install friction make this a solid choice for Substrate blockchain development. The 16 dependencies are well-established cryptographic and networking libraries. Install if you need to interact with Polkadot, Kusama, or other Substrate chains from Python.
Install
substrate-interface on PyPI
Before you install
Low friction installation with a pure-Python wheel. Actively maintained with recent commits and no known vulnerabilities. Supports Python 3.7 through 3.11.
Requires a running Substrate node RPC endpoint (local or remote) or uses embedded light client via smoldot-light; WebSocket connectivity needed.
License in practice
Licensed under Apache Software License (permissive), allowing commercial and private use with minimal restrictions.
Quickstart
pip install substrate-interface
from substrate_interface import SubstrateInterface
substrate = SubstrateInterface(url="ws://127.0.0.1:9944")
result = substrate.query('System', 'Account', ['F4xQKRUagnSGjFqafyhajLs94e7Vvzvr8ebwYJceKpr8R7T'])
print(result.value['data']['free'])Verify before relying
- Performance characteristics when querying large datasets or high-frequency RPC calls
- Compatibility scope with runtimes older than MetadataV14 or under active development
Package facts
| License | permissive license permissive |
| Python support | Supports the current Python release <4,>=3.7 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | 16 packageswebsocket-clientbase58certifiidnarequestsxxhashecdsaeth-keyseth_utilspycryptodomePyNaClscalecodecpy-sr25519-bindingspy-ed25519-zebra-bindingspy-bip39-bindingssmoldot-light |
| Maintenance | Actively maintained 206 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 261,738 / month, #8,382 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Development Status :: 5 - Production/StableIntended Audience :: DevelopersLicense :: OSI Approved :: Apache Software LicenseProgramming Language :: Python :: 3Programming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.7Programming Language :: Python :: 3.8Programming Language :: Python :: 3.9 |
Evidence: substrate_interface-1.8.1-py3-none-any.whl
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See also async-substrate-interface · scalecodec · smoldot-light · cyscale · bittensor-wallet · aptos-sdk · cosmpy · rlp · stellar-sdk · tonsdk