Overview

Mero DevTools (mero-devtools-js) is a monorepo of JavaScript/TypeScript tooling for building Calimero apps. It exists to remove the hand-written glue between a compiled WASM contract and the TypeScript frontend that calls it: given the contract’s ABI, it generates a fully-typed client so every method call is checked by the compiler.

What’s in the box

The repository is a workspace with three packages:

@calimero-network/abi-codegen

The published package. A WASM-ABI v1 parser plus a TypeScript client generator, exposed both as the calimero-abi-codegen CLI and as a programmatic library. This is the core of the toolset.

create-mero-app

A separate scaffolding CLI (npx create-mero-app) that clones a starter template — a Rust or JavaScript kv-store with a React frontend — into a new project directory.

codegen-example

A private reference app (not published) showing the generated output for the ABI conformance fixture, wired into a React UI with @calimero-network/mero-react.

The core idea: ABI in, typed client out

A Calimero application is compiled to WASM. Alongside the module, the build emits a WASM-ABI v1 manifest — a JSON description of the contract’s public surface: its methods, events, and named types. abi-codegen reads that manifest and emits a single TypeScript file containing:

• an interface / type for every named type in the manifest,
• payload and error types for events and fallible methods,
• a client class with one typed async method per contract method.

Each generated method wraps a single RPC call against the MeroJs runtime, so your frontend calls await client.setValue({ key, value }) instead of assembling contextId / method / argsJson payloads by hand.

One file, no separate types module

The CLI emits exactly one file, <ClientName>.ts, with the type definitions and the client class together — types are not written to a separate module.

A typical workflow

1. Build your contract and obtain its abi.json manifest.
2. Generate the client: calimero-abi-codegen -i abi.json -o src/generated.
3. Use it in your app: construct the client with a MeroJs instance, a contextId, and an executor public key, then call its methods.

import { KVStoreClient } from './generated/KVStoreClient';

// `mero` comes from the MeroProvider / useMero() hook in @calimero-network/mero-react
const client = new KVStoreClient(mero, contextId, executorPublicKey);

await client.set({ key: 'greeting', value: 'hello' });
const value = await client.get({ key: 'greeting' });

Where to go next

ArchitectureInside the codegen pipeline — parse, model, generate, emit — and the create-mero-app scaffolding flow.

CLI referenceEvery command and flag for calimero-abi-codegen and create-mero-app.

ABI formatThe WASM-ABI v1 manifest the generator reads.