The Breez SDK enables mobile developers to integrate Lightning and bitcoin payments into their apps with a very shallow learning curve. The use cases are endless – from social apps that want to integrate tipping between users to content-creation apps interested in adding bitcoin monetization. Crucially, this SDK is an end-to-end, non-custodial, drop-in solution powered by Greenlight, a built-in LSP, on-chain interoperability, third-party fiat on-ramps, and other services users and operators need.

The Breez SDK provides the following services:

• Sending payments (via various protocols such as: bolt11, keysend, lnurl-pay, lightning address, etc.)
• Receiving payments (via various protocols such as: bolt11, lnurl-withdraw, etc.)
• Fetching node status (e.g. balance, max allow to pay, max allow to receive, on-chain balance, etc.)
• Connecting to a new or existing node.

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This diagram is a high-level description of the Breez SDK:

This module handles everything related to the signing of lightning messages. It is initialized with the user’s seed.

This module parses user input that is related to sending and receiving of payments. It identifies the protocol (lightning, lnurl-pay, lightning address, lnurl-withdraw, btc address, etc.) and the related data. Apps should use this parser to interpret users input, display the details to users and then execute the specific action (pay or receive).

This is an interface that defines how the SDK interacts with the user’s Lightning node. The interface defines methods to create a new node, connect to an existing node, pay or create invoices. It also provides access to the node’s low-level functionality such as: listing peers, graph information etc. Currently we only have one provider (Greenlight) but we can add more providers in the future.

This module provides the ability to send or receive on-chain payments via submarine swaps. Send to a BTC address is done by a reverse submarine swap and receive by a regular submarine swap. It includes refund functionality as well.

This module provides fiat currencies conversion services and fiat on-ramp service (via MoonPay).

This module provides the interface of interacting with one or more LSPs.

The libs folder contains three sub folders and is a structured as a cargo workspace:

• sdk-core: the core SDK rust library.
• sdk-bindings: ffi bindings for Kotlin & Swift.
• sdk-flutter: a flutter plugin (includes ffi bindings for dart).

The tools folder contains a simple command line interface (sdk-cli) to the SDK See instruction in each sub project readme on how to build, test and run.

To get started with the Breez SDK API, please follow the documentation here.

• ‘On-the-fly’ channel creation
• Send/receive bolt11
• LNURL-Pay
• LNURL-Withdraw
• Backup/restore using mnemonics
• Send zero-amount invoices
• Fiat currencies
• Send spontaneous payments
• Send to a Lightning address
• Send to BIP 21
• cli inteface
• Swift bindings
• Kotlin bindings
• API key
• Receive via on-chain address
• Send to an on-chain address
• React Native bindings
• LNURL-Auth
• MoonPay fiat on-ramp
• Spend all funds
• Mobile Notifications
• Offline receive via notifications
• Performance optimizations
• Close channels to a predefined address
• Make mempool.space dependency optional
• Receive 0 amount invoice via LSP (unified QR)
• Send/receive bolt12
• Async payments
• LDK support
• Splicing
• WebAssembly support