LDK (Lightning Dev Kit)

Modular Rust library for Lightning. Used by Cash App, Casa, ldk-node, more. Mutiny Wallet was a prominent early user; the shutdown was announced 2024-08-05 and the hosted wallet closed 2024-12-31. Its repos took their last commits in September 2024 and are archived today, so treat Mutiny references below as history, not as a live deployment.

See full overview at ../../lightning/ldk/SKILL.md.

Crates

lightning — core protocol logic.
lightning-net-tokio — async TCP transport.
lightning-persister — file persistence.
lightning-background-processor — task driver.
lightning-block-sync — chain sync via bitcoind RPC.
lightning-transaction-sync — chain sync via Esplora / Electrum.
lightning-rapid-gossip-sync — fast initial gossip.
lightning-invoice — BOLT11 invoice handling.
ldk-node — opinionated bundled crate.
lightning-liquidity — LSP client/server.

Release lines (as of September 2026)

lightning and the sibling core crates — 0.2.6 (2026-09-09). LDK 0.1 (January 2025) was the API-stabilisation milestone; since then the project ships features in minor releases and backports fixes as patch releases on older minor lines.
lightning-invoice — 0.34.1 (June 2026).
ldk-node — 0.7.0 (2025-12-03), which depends on the lightning 0.2 line. main carries an unreleased 0.8.0.
Next major: lightning 0.3.0-rc1 and lightning-invoice 0.35.0-rc1, both published 2026-08-31. No stable 0.3 yet.

ldk-node 0.7.0 added experimental channel splicing, async payments (serving and paying static invoices), a Bitcoin Core REST chain source, and persisted liquidity-service state.

ldk-node quickstart

[dependencies]
ldk-node = "0.7"

use ldk_node::Builder;
use ldk_node::bitcoin::Network;
use ldk_node::lightning_invoice::{Bolt11InvoiceDescription, Description};

let mut builder = Builder::new();
builder.set_network(Network::Bitcoin);
builder.set_chain_source_esplora(
    "https://mempool.space/api".to_string(), None);
builder.set_storage_dir_path("/path/to/data".to_string());

let node = builder.build()?;
node.start()?;

let description = Bolt11InvoiceDescription::Direct(
    Description::new("Test".to_string())?);
let invoice = node.bolt11_payment().receive(
    100_000,        // 100k msat
    &description, 3600,
)?;

Builder setters take &mut self, so build the builder in a let mut binding rather than chaining off a temporary. Network is re-exported as ldk_node::bitcoin::Network, not ldk_node::Network.

Bindings (as of September 2026)

Two separate binding families exist and are not interchangeable: ldk-node 0.7.0 ships UniFFI bindings for Swift, Kotlin and Python (plus community Flutter bindings), while an older family is generated directly over the raw lightning crate on top of ldk-c-bindings. Each entry below says which family it belongs to.

ldk-swift — iOS/macOS, generated over raw lightning, not over ldk-node; the SwiftPM product is named LightningDevKit. Not archived, but no release or commit since 0.0.125 (2025-02-27), so it is still on the pre-0.1 0.0.x line and does not track lightning 0.2.
ldk-garbagecollected — Java, C# and TypeScript over raw lightning. Java ships as org.lightningdevkit:ldk-java 0.2.5.0 on Maven Central and TypeScript/WASM as the npm lightningdevkit package 0.2.5-0, both published 2026-09-01. There is no separate Kotlin/Android binding over raw lightning — Android consumers use the Java bindings.
ldk-node-jvm / ldk-node-android — ldk-node's UniFFI Kotlin bindings, both 0.7.0 on Maven Central (2025-12-03).
ldk-node-flutter — Flutter over ldk-node, maintained by LtbLightning.

lightningdevkit/ldk-nodejs — an older Node.js binding — is archived and took its last commit in May 2022. The maintained JS/WASM path is the lightningdevkit npm package above, which wraps raw lightning; there is still no ldk-node WASM/JS binding.

Use cases

Mobile Lightning wallets.
Browser-based LN — Mutiny compiled lightning to WASM before shutting down in 2024; the pattern is still viable, but there is no maintained ldk-node WASM/JS binding to build on.
Custom backend services with Lightning embedded.

Compared

See ../../lightning/ldk/SKILL.md for LND/CLN comparison and full feature matrix.

Version floor and security history (as of September 2026)

0.2.6 (2026-09-09) is the floor on the 0.2 line. It fixes a denial-of-service where a bogus HTLC that is immediately rejected, after a second HTLC with the same payment_hash was already forwarded, could leave the ChannelManager unreadable on deserialization; and a fee-inflation bug letting a malicious splice counterparty make us over-allocate fee into their output when we contribute to a splice.
0.2.5 and 0.1.12 (both 2026-08-05) fixed an on-chain funds-theft vulnerability for forwarding nodes that accept channels from untrusted peers — ChannelMonitor confused two HTLCs with equal payment_hash and amount and resolved them incorrectly — plus several remote-panic DoS vectors (oversized protocol messages, invalid onion-message reply paths, reorg-time claim batching, and the 50-unfunded-peer limit not being enforced).
0.2.3 (2026-06-18) is superseded by the 0.2.6 floor but worth knowing about: it fixed anchor-reserve underestimates that could leave a node unable to properly force-close, possiblyrandom not generating random data unless explicitly configured (leaving LDK open to HashDoS), and several remote-triggerable panics.
The 0.1 line received no backport of the 0.2.6 fixes, so 0.1.12 is not a current floor. Move to 0.2.6.
ldk-node 0.7.0's manifest requires lightning 0.2.0, which is a caret requirement — a fresh resolve picks up 0.2.6, but an existing Cargo.lock needs cargo update -p lightning to actually land on it. Check the lockfile, not the manifest.

Migrating to 0.3 (release candidate as of September 2026)

lightning 0.3.0-rc1 changes defaults and invalidates some persisted state. Plan for:

ChannelHandshakeConfig::negotiate_anchors_zero_fee_htlc_tx now defaults to true.
UserConfig::manually_accept_inbound_channels is removed — it is always on, so inbound channels must be accepted explicitly from event handling. ChannelHandshakeLimits::max_funding_satoshis went with it.
Payment metadata is now committed to in the payment secret, so BOLT11 invoices already issued with payment metadata are invalidated on upgrade (and newly issued ones on downgrade). This bites anyone holding long-lived invoices.
Blinded-path receives are authenticated with a ReceiveAuthKey; 0.3+ will not accept payments over blinded paths created by earlier versions. Existing BOLT12 offers stay valid; issued-but-unclaimed BOLT12 refunds do not.
Splices can be RBF'd and can add and remove funds in the same splice. A splice negotiated on an earlier version cannot be RBF'd, and downgrade after an RBF is unsupported.
MSRV rises to rustc 1.75.

During the 0.3 cycle primary rust-lightning development moved to git.rust-bitcoin.org; GitHub remains a synchronised mirror with issues forwarded.

Common pitfalls

Persist trait misimplementation → state corruption.
Async signer race conditions.
Version migrations require careful state migration.
Pinning a major without tracking its patch line — LDK backports security fixes as patch releases, so 0.2 alone is not a floor.

bitcoin-libraries-ldk