Building a Threshold-Based Token Sweeper with Mimic Protocol

Managing token balances across wallets can be tedious. Sending funds manually is error-prone and time-consuming. Luckily, Mimic Protocol lets you automate token transfers with a Token Sweeper, moving funds automatically when a balance threshold is reached.

In this post, I’ll walk through how to set up a Token Sweeper using Mimic in TypeScript / AssemblyScript.

1. Install the Mimic CLI

First, install the Mimic CLI globally:

yarn global add @mimicprotocol/cli

Verify the installation:

mimic

2. Initialize a New Project

Create a new Mimic project for your Token Sweeper:

mimic init -d token-sweeper
cd token-sweeper
ll

This generates a TypeScript project with:

• package.json
• src/ folder for core logic
• manifest.yaml with task metadata and configurable inputs

3. Edit the Manifest

Update manifest.yaml to reflect the Token Sweeper logic:

version: 1.0.15
name: Transfer based on USD threshold
description: Automated task to execute parameterized transfers based on balance threshold in USD
inputs:
  - chainId: uint32
  - token: address
  # - amount: string # e.g., '10.2' = 10.2 of the given token
  - recipient: address
  - maxFee: string # e.g., '0.01' = 0.01 of the given token
  - thresholdUsd: string # e.g., '30.5' = 30.5 USD
abis:
  - ERC20: ./abis/ERC20.json

Delete any unnecessary inputs (like amount) and create the abis folder:

mkdir -p abis
wget "https://216358192-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F2K6E4Us9xYRIC0Tt0SIZ%2Fuploads%2FLzvR464ArklTLEA67qfw%2FERC20.json?alt=media&token=163296d8-8fd0-4376-a649-4c7c07f8b321" -O ./abis/ERC20.json

4. Generate Typed Code

Run:

mimic codegen

This generates:

• src/types/ERC20.ts → typed wrapper for ERC20 contracts
• src/types/index.ts → typed access to task inputs

Typed code allows safe, clean interaction with contracts and inputs.

5. Write the Task Logic

Tasks are written in AssemblyScript, a strongly-typed subset of TypeScript that compiles to WebAssembly:

import {
  ERC20Token,
  environment,
  log,
  TokenAmount,
  TransferBuilder,
  DenominationToken,
  USD,
} from "@mimicprotocol/lib-ts";
import { ERC20 } from "./types/ERC20";
import { inputs } from "./types";

export default function main(): void {
  const token = ERC20Token.fromAddress(inputs.token, inputs.chainId);
  const threshold = USD.fromStringDecimal(inputs.thresholdUsd);
  const wallet = environment.getContext().user;
  const balance = new ERC20(inputs.token, inputs.chainId).balanceOf(
    wallet,
  ).value;
  const balanceUsd = TokenAmount.fromBigInt(token, balance).toUsd();

  if (balanceUsd.isError) throw new Error(balanceUsd.error);

  log.info(`Source wallet balance: ${balance}`);
  log.info(`Source wallet balance in USD: ${balanceUsd.value}`);

  if (balanceUsd.value.gt(threshold)) {
    TransferBuilder.forChain(inputs.chainId)
      .addTransferFromBigInt(token, balance, inputs.recipient)
      .addMaxFee(
        TokenAmount.fromStringDecimal(DenominationToken.USD(), inputs.maxFee),
      )
      .build()
      .send();
  }
}

This task monitors wallet balances and automatically transfers tokens if the USD threshold is exceeded.

6. Compile and Deploy

Compile the task and manifest:

mimic compile

This produces:

• build/task.wasm → WebAssembly binary
• build/manifest.json → processed manifest

Generate an API key at Mimic API and deploy:

mimic deploy --key $MIMIC_API_KEY

Your task template is now live! Verify via IPFS:

https://ipfs.io/ipfs/<CID>

7. Configure & Test

1. Configure the task in Mimic’s web UI
2. Sign & send the task
3. Fund the wallet with USDC
4. Watch Mimic automatically sweep the tokens when the threshold is reached

8. Beyond Token Sweeping

Mimic isn’t just for wallet automation. You can use it for:

• Dollar-cost averaging (DCA)
• Token rebalancing
• Fee collection
• Refund automation
• Chained workflows like bridging assets or investing in Aave

Resources

• Mimic Protocol
• ERC20 ABI
• Code for this tutorial: mcmoodoo/mimic-token-sweeper

Conclusion

Automating token transfers with Mimic saves time, reduces errors, and opens up possibilities for advanced workflows. This Token Sweeper is a simple example of what’s possible—explore further and see what else you can automate!

Follow @mimicfi on X for updates