Introduction

Midday SDK is a developer-friendly SDK for building decentralized applications (dapps) on the Midnight Network.

What is Midnight Network?

Midnight is a data-protection blockchain that uses zero-knowledge proofs to enable privacy-preserving smart contracts. It allows developers to build applications where sensitive data remains private while still being verifiable on-chain.

Why Midday SDK?

The official Midnight JavaScript libraries are powerful but can be complex to work with. Midday SDK provides:

• Simplified API - High-level abstractions that reduce boilerplate
• Multiple Programming Styles - Choose between Promise API, Effect API, or Effect with Dependency Injection
• Browser Support - First-class support for browser environments with Lace wallet integration
• Type Safety - Full TypeScript support with typed contract actions and state
• Effect Integration - Built on Effect for robust error handling and composability

API Styles

Midday SDK offers three ways to interact with contracts:

Promise API

The simplest approach, ideal for quick prototypes or developers unfamiliar with Effect:

const loaded = await client.loadContract({ module: CounterContract, zkConfig, privateStateId: 'my-id' });
const deployed = await loaded.deploy();
await deployed.actions.increment();
const state = await deployed.ledgerState();

Effect API

For developers who want functional programming benefits without dependency injection:

const program = Effect.gen(function* () {
  const loaded = yield* client.effect.loadContract({ module, zkConfig, privateStateId: 'my-id' });
  const deployed = yield* loaded.effect.deploy();
  yield* deployed.effect.actions.increment();
  return yield* deployed.effect.ledgerState();
});

Effect with Dependency Injection

For large applications that benefit from testability and modularity:

const program = Effect.gen(function* () {
  const client = yield* Midday.Client.MiddayClientService;
  const loaded = yield* client.effect.loadContract({ module, zkConfig, privateStateId: 'my-id' });
  const deployed = yield* loaded.effect.deploy();
  yield* deployed.effect.actions.increment();
  return yield* deployed.effect.ledgerState();
});

Next Steps

Ready to get started? Head to the Quick Start guide.