iOS App

Henceforth

Bitcoin meets Forth.

A full Forth-2012 compliant interpreter with an integrated Bitcoin SV wallet, running natively on your iPhone and iPad.

henceforth

$ 2 3 + .

5 ok.

$ : square dup * ;

ok.

$ 7 square .

49 ok.

── Bitcoin ──────────────────────────

$ wallet-balance .

1,250,000 sats ok.

$ tx-new 10000 s" 1A1z...fNa" tx-add-output tx-broadcast

Transaction broadcast. txid: 3a7f...c9e1 ok.

$ _

Learn more

Henceforth is a pocket-sized programming environment built around FORTH — a minimal, stack-based language from 1970 that fits an entire interpreter into a few thousand lines of code. On iOS, that means you carry a real programming language in your pocket, not a playground or a sandbox.

Write definitions, build stacks, save words, and compose new behaviours on the fly. The interpreter is Forth-2012 compliant, so anything you write works in any standard FORTH implementation on any platform.

Capabilities

133CORE Words

Full Forth-2012 CORE compliance. Stack operations, arithmetic, comparison, control flow, defining words, pictured output, and more.

350+Total Vocabulary

Beyond the standard: 140+ Bitcoin Script opcodes, transaction builder words, blockchain API access, graph plotting, and file management.

BRC-42Key Derivation

Type42 key derivation for deterministic address generation. Send and receive BSV with modern cryptographic key management.

SPVVerification

Simplified Payment Verification built in. Merkle proofs validate transactions without trusting a third party — exactly as Satoshi described.

ARCBroadcasting

Direct transaction broadcasting via ARC with automatic failover. Build, sign, and broadcast transactions from the FORTH terminal.

BRC-2Encryption

End-to-end message encryption using ECIES. Wire-compatible with the BSV SDK. Paymail support with BRC-30 peer-to-peer protocol.

Engineering

Native Swift, end to end. The Bitcoin layer is built on the open-source SwiftBSV SDK.

Built with

SwiftBSV

Open-source Swift SDK for Bitcoin SV — Type42 key derivation, SPV verification, ARC broadcast, BRC-2 encryption.

GitHubRead the SwiftBSV book (41 pages, PDF)

Engineering

Native Swift, end to end

Henceforth is a native iOS app written in Swift — no React Native, no web view wrapper. The FORTH interpreter runs directly on the device, and the Bitcoin layer talks to the network from the same process.

The interpreter

Forth-2012 compliant — 133 CORE words plus 200+ extensions for graphics, file I/O, Bitcoin operations, and terminal control. Custom words are first-class: define : square dup * ;, use it immediately, save it to disk.

140+ Bitcoin Script opcodes are exposed as FORTH words, so you can compose locking scripts, simulate spending conditions, and step through opcode-level behaviour interactively — not in a textbook.

Bitcoin via SwiftBSV

The wallet layer is built on SwiftBSV, an open-source Swift SDK for Bitcoin SV. Type42 (BRC-42) key derivation gives deterministic addresses without HD-wallet plumbing. SPV verification validates transactions against block headers — Merkle proofs, no third-party trust. ARC handles broadcasting with automatic failover. BRC-2 (ECIES) encrypts messages wire-compatibly with the TypeScript BSV SDK.

Because the wallet is exposed as FORTH words, you can build, sign, and broadcast transactions from the terminal (tx-new ... tx-add-output tx-broadcast) — the interpreter treats Bitcoin as just another vocabulary.

Documentation

Complete reference for all FORTH words and Bitcoin Script opcodes, plus long-form articles and video tutorials. All on the web — use the navigation above to jump between docs, articles, and learn.

Henceforth app icon

Available now

Download on the App Store