Light Client Wallet Integration

User-verifiability shapes into your wallet!

Note: We are in the Alpha Testnet stage, so the API may undergo incompatible changes in the future. If you encounter any issues, please join our Discord to get in touch with the Nubit Team.

We have developed a Modular Indexer (Light) JavaScript SDK for running Modular Indexer (Light) inside your wallets, websites, Chrome extensions, and more!

We extended the functionalities of the UniSat Wallet extension (version v1.3.0) via integrating Nubit modular-indexer-light-sdk to verify the BRC-20 balances by wallet users locally.

See our demos for the UniSat wallet extension. More wallet integration on the way!

By clicking the Verify button, we fetch the verified checkpoints from official Nubit Modular Indexer (Committee) instances and do a double verification on the balance proofs. Once it's successful, we display the proofs on the tooltip.

Upon malicious checkpoints, the tooltip would list all the commitments of the checkpoints and the SDK would try doing a reconstruction using the last consistent checkpoint.

Here are some screen recordings for showcasing the verification demo.

Integrate the Modular Indexer (Light) SDK

For users who are interested in trying out this SDK, you can follow the installation instructions and examples provided below. Please feel free to reach out to the Nubit team for any questions or feedback.


Note: Our JavaScript SDK is only available on the web (browsers), since it introduces web workers for better performance, and they are currently not supported on JavaScript runtimes like Node.js.

Install via npm or other package managers:

npm i @nubit/modular-indexer-light-sdk


The following example shows how to get the verified balance with a given tick and wallet address.

import {create} from "@nubit/modular-indexer-light-sdk";

// Create the SDK first.
const sdk = await create();

// Run SDK with configurations.
    "committeeIndexers": {
        "s3": [
                "region": "us-west-2",
                "bucket": "nubit-modular-indexer-brc-20",
                "name": "nubit-official-00"
        "da": []
    "verification": {
        "bitcoinRPC": "",
        "metaProtocol": "brc-20",
        "minimalCheckpoint": 1

// Get the SDK status, e.g. `verifying`.
console.log(await sdk.getStatus());

// Some code here to wait for the SDK status being `verified`...

// If the SDK status becomes `verified`, get the balance.
console.log(await sdk.getBalanceOfWallet("ordi", "123abc456def"));


In the toplevel project directory, run this make command to build the WebAssembly module:

make GOOS=js GOARCH=wasm packages/modular-indexer-light-sdk/modular-indexer-light.wasm

And then go back here to start the development server:

cd packages/modular-indexer-light-sdk/
npm run dev

Before publishing a new package, bump the version first, and then do the dry-run:

npm run build
npm pack # to check the list of bundled files
npm publish --access=public

How it works?

Modular Indexer for the greater good

Check out Modular Indexer (Committee) for the technical details about our user-verifiable execution layer.

WebAssembly for seamless integration

Modular Indexer (Light) is a web service and library in Go, and Go officially supports compiling code into WebAssembly. With this, the possibility of integrating Modular Indexer (Light) everywhere becomes reality.

Web workers for smoother interactivity

Loading and warming up a WebAssembly module inside the main JavaScript thread would be a disaster, where it could freeze the UI and annoy our users.

We start a new web worker to tame the beast of it and communicate with the worker via posting messages.


create(): Promise<SDK>

Create the SDK instance. Config): Promise<void>

Load the WebAssembly module and get everything started.

SDK.getStatus(): Promise<Status>

Get the SDK status, it could be:

  • "verifying": Still verifying the checkpoints from committee indexers

  • "verified": All checkpoints are verified and consistent to retrieve user data for good

  • "unverified": Checkpoints seem inconsistent and a further reconstruction of checkpoints starts to run

SDK.getBlockHeight(): Promise<number>

Get the current Bitcoin block height.

Throws an error if SDK is still verifying.

SDK.getBalanceOfPkScript(tick: string, pkscript: string): Promise<BalanceOfPkScript>

Get verified balances via PkScript.

Throws an error if SDK is still verifying.

SDK.getBalanceOfWallet(tick: string, wallet: string): Promise<BalanceOfWallet>

Get verified balances via a wallet address.

Throws an error if SDK is still verifying.

SDK.getCurrentCheckpoints(): Promise<Checkpoint[]>

Get current checkpoints from all the committee indexers, for introspection. A checkpoint contains useful information like commitments to track down malicious ones.

Throws an error if SDK is still verifying.

SDK.getLastCheckpoint(): Promise<Checkpoint>

Get the previous checkpoint that is proven to be consistent. This checkpoint could be used internally to reconstruct a new and trusted checkpoint when some malicious committee indexers exist.

Throws an error if SDK is still verifying.

Last updated