God of the sea, master of the trident (forks)
Neptune is a browser wallet for developers. It consists of a browser extension and a local backend, with which you can manage state across multiple dev environments, impersonate other addresses, test frontend features, and do anything that you’d do with mainnet but in a simulated environment.
The current version is not considered stable.
Currently, the extension and backend must both be built from source. We’re working to create a first stable release soon. Start by cloning this repo.
Build the extension. You can input your RPC URL as an environment variable now (PROVIDER_RPC_URL),
or via the browser extension later.
cd extension
PROVIDER_RPC_URL=<your-rpc-url> pnpm build
# or
yarn build
# or
npm run build
Then,
Then run the backend:
cd server
make setup # only for first-time setup
make build
./build/neptune-<version>-<arch/os> # name will depend on your machine
Once installed, you can interact with Neptune via the browser extension.
Current features include:
- Fork directly from mainnet to gain access to a local fork for development
- Run transactions against your local forks via the Neptune browser extension
- Impersonate any other address, and run transactions on forks as these wallets
- Rewind, replay, and reset the state of your forks
- Use most dapps with Neptune to simulate actions on their frontends - without modifying their frontend
- Create a new fork from an already existing fork to create multiple local environments with different configurations
- Seamless interop with metamask - simply connect and disconnect when you want to use one or the other
Try out various dapps, try acting as vitalik, run multiple forks with different configurations, run txns forward and backwards, and more! Let us know how it's working for you, and if there are any features you'd like to see in a future version.
Note that the server currently runs entirely in memory - if you kill the server, you will lose access to the states of your forks, and need to reset. We're exploring options for persistent storage.
You can run forked environments on many dapps (try making a swap on Uniswap with your neptune Wallet - you can run it as a simulation). But there are some dapps where it won't work. We do our best to intercept any reads to the chain and redirect them to a fork, but if a dapp uses data sources besides the RPC URL, we can't intercept that (we don't have the infra to spin up a new subgraph for every new fork, but sounds like a fun, challenging project).
We welcome contributions from everyone. If you have questions, feel free to head over to the discussions forum to chat or introduce ideas for features.
GNU General Public License V3, see LICENSE.
The server is based on foundry’s anvil, extended with some Neptune specific functionality. The extension is based on ArgentX. Huge thanks to the contributors from both of these teams - this wouldn't have been possible without you.