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Solidity re-compiler that can be used to verify that bytecode corresponds to certain source code

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Sourcify 🧑‍💻📝🔍

Sourcify wants to help make contract interactions on the blockchain safer and more transparent for users.

To achieve this goal, Sourcify supports several efforts to foster adoption of open-source source file verification, metadata files and NatSpec comments.

ℹ️ This repository only contains the main components, the Sourcify monorepo with main services and the verification UI. The Sourcify Github organization contains all other auxiliary services and components.

At its core, Sourcify currently maintains:

  • an interface that helps developers to verify metadata and contract source code. It is accessible via and sourcify.eth.
  • a decentralized contract repository of all verified contracts, powered by IPFS, accessible via and verificat.eth.
  • a monitoring & verifier service that checks for new contracts on selected EVM-compatible chains and tries to verify them automatically.
  • verify & fetch plugins for several IDEs.

Sourcify aims to provide a base layer allowing other tools build on top of it. Its main purpose is to keep metadata and source files available via IPFS and Swarm (preventing that the links in the bytecode turn into dead links).

Besides the technical infrastructure, Sourcify is also a collective initiative to bring transparency and awareness to the space. We want to educate and build bridges between development tools, wallets, interfaces and other components which all play an important role in demystifying interaction with smart contracts for the end user and hence making blockchain interactions safer.

Have questions or improvement ideas?

💬 Chat with us on Gitter or Discord (channels are bridged).

🌐 Follow us and help us spread the word on Twitter.

The Basic Concept

Sourcify verifies that Ethereum bytecode was compiled from a certain Solidity source code and maintains a public repository of contract metadata.

The repository indexes metadata with IPFS or Swarm hashes which the solc compiler embeds in contract bytecode. By fetching code on-chain and extracting this hash, it is possible to obtain related metadata from Sourcify's records.

Read more about Sourcify in the FAQ. Information on metadata can be found in Solidity documentation.

The Technical Details

As mentioned above, Sourcify has several components:

  • a "monitoring & verifier service" which watches public Ethereum networks for contract deployments and tries to associate them with sources and metadata published to Swarm or IPFS. It currently watches:

    • Ethereum Mainnet
    • Ropsten
    • Rinkeby
    • Kovan
    • Goerli
    • xDai
    • Matic Mainnet
    • Matic Testnet Mumbai
    • Binance Smart Chain Mainnet (monitoring temporarily suspended)
    • Binance Smart Chain Testnet (monitoring temporarily suspended)
  • a website which allows you to submit sources and metadata for a specific contract address manually

    • (Stable)
    • (Unstable)
  • a public metadata repository that contains uploaded (or discovered) metadata and their sources:

    • (Stable)
    • (Unstable)

Getting Metadata

Using solc directly on the commandline:

solc --metadata --metadata-literal 

or with JSON/IO

  "settings": {
    "metadata": { "useLiteralContent": true }

Using the Monitoring Service

If your Solidity code compiles with solc >= 0.6.0, all you need to do is to upload your contract metadata and sources to IPFS as part of your deployment process. The monitoring service will automatically add your files to the metadata repository when it sees your contract created on the network.

A simple example for Truffle projects can be found at cgewecke/metacoin-source-verify which contains a script to publish to IPFS directly from a Truffle compilation artifact.

Security Precautions

Please note that source code verification is only reliable if it is performed on the creation bytecode, i.e. the bytecode payload used when the contract was created. The deployed bytecode, i.e. the bytecode stored in the blockchain as code is not sufficient, because the constructor can still be different and set arbitrary storage entries.

Furthermore, if the constructor requires parameters, these have to be checked as well.

Also note that there can still be differences in the source code that are not visible in the bytecode. Variables can be renamed or unused code can be introduced. Since the bytecode contains a hash of the source code, such modifications have to be prepared at deploy time, but it is still a possibility.

Using the Repository

There is a repository which contains all the files that the monitoring service has found on the networks that are being watched.

The repository is accessible via this link.

The repository UI currently looks like this:

It offers the option to search, donwload or open folders.

For example to download:

Or if you want to search something:

The metadata inside is visible as raw, and can be downloaded like that:

Alternatively, if you want to take a look at the contract in the browser, you can open it like this:

Future Plans

  • cope with metadata that does not have in-place source code
  • automatically retrieve the metadata and the source code from SWARM or IPFS, so you only need to supply the metadata hash or bytecode
  • perform source verification given only an address instead of the bytecode or the metadata

How to

Install and run server with UI

$ npx lerna bootstrap
$ npx lerna run build
$ npm run server:start
$ npm run dev:ui

Run inside docker




How to run

Prepare environment and start by running these commands from the

directory: To build images locally run:
docker-compose -f geth.yaml -f ipfs.yaml -f localchain.yaml -f monitor.yaml -f repository.yaml -f s3.yaml -f server.yaml -f ui.yaml -f build-ipfs.yaml -f build-localchain.yaml -f build-monitor.yaml -f build-repository.yaml -f build-s3.yaml -f build-server.yaml -f build-ui.yaml build --parallel

If you just want to run it do:

docker-compose -f ipfs.yaml -f localchain.yaml -f monitor.yaml -f repository.yaml -f s3.yaml -f server.yaml -f ui.yaml up -d
(-d flag means that output won't be printed in stdout)

Note: you don't need to run all the services, just the ones you want.

How to run



cp .env.testing .env
docker-compose -f ipfs.yaml -f localchain.yaml -f monitor.yaml -f repository.yaml -f s3.yaml -f server.yaml -f ui.yaml up -d

Other approach would be to run every service in docker except one that you are working on.

This will build the project in docker containers, launching the monitor and server. Verified sources and contract addresses will be stored in

folders in your project root. The directories are created automatically if they don't exist.

will be served to http://localhost:1234


To help with manual UI testing, some contracts whose sources and metadata can be found in the

folder are automatically deployed to a local ganache instance running on port 8545. Their contract addresses are deterministically generated at:

| Contracts | Addresses | | --------- | --------- | | Simple.sol | 0x8168f192F7432C93FCb16e039B57FB890AaB3230 | | SimpleWithImport.sol | 0x0Ef7de872C7110d6020fa5e62d7cD31Fd90FF811 |

Similar sources are also pre-deployed to Ropsten and can be found in the


| Contracts | Addresses | | --------- | --------- | | Simple.sol | 0xEB6Cf7952c666F81f1a5678E80D4fC5Ce3a7bF0b | | SimpleWithImport.sol | 0x4668b709182F41837c4e06C8de1D3568df7778D9 |

Shutdown Stop the docker run with

. To remove exited containers type
docker-compose -f server.yaml -f ... down
. You can list all previously started containers with


Run tests with:

lerna run test

contains contracts, compilation artifacts and metadata files which can be used for building test cases.
  • contracts/: Solidity files (browser tests)
  • metadata/: raw metadata files (browser tests)
  • pass/: compilation artifacts which should verify (unit tests)
  • fail/: compilation artifacts which should not verify (unit tests)
  • compiler.json: compiler config for generating more cases

Test sources are compiled with 0x's sol-compiler. This lets you pick any compiler version or settings by modifying the

file as needed.

To generate more test data, go to the

directory, add Solidity files to the
folder and run:
npx sol-compiler

Compilation artifacts will be written to an



We also provide publicly available API for both environments that you can use. You can find examples in our Postman collection in the root of this project


Server API

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