Open-source documentation graph for building cash management products on EVM-based distributed ledgers (permissioned + permissionless).
Companion to
paycodex— same cash management products mapped onto DLT. Cross-linked.
- 5 foundation notes — DLT primer, EVM stack, cash legs comparison, bank integration, compliance
- 37 concept atoms — Solidity, Hardhat, OpenZeppelin, AA, MPC, oracles, bridges, indexers, security patterns
- 12 ERC standards deep dives — ERC-20, 721, 1155, 1400, 3643 (T-REX), 4626, 4337 (AA), 2535 (Diamond), 2612 (permit), 7281 (xERC20), 1967
- 15 platforms — Ethereum L1, Base, Arbitrum, Optimism, zkSync, Polygon, Linea, Besu, Quorum, Canton EVM, Fabric, Corda
- 5 cash leg types — stablecoin, tokenized deposit, wholesale CBDC, retail CBDC, tokenized MMF — full comparison matrix
- 14 bank integrations — Temenos, SAP, Oracle, Microsoft Dynamics, Thought Machine, Mambu, Avaloq, Finacle, Kyriba, Volante, Form3, Finastra
- 9 compliance patterns — Travel Rule on-chain, T-REX, MiCA, FINMA DLT Act, EU DLT Pilot Regime, Basel III crypto, OFAC on-chain
- 7 architecture patterns — bank-DLT rail, tokenization platform, multi-chain treasury, permissioned-public bridge, atomic DvP, gasless paymaster
- 6 ADRs — public vs permissioned, cash leg strategy, T-REX vs 1400, multi-chain, AA, build vs Tokeny
- Top 100 ranked use cases — easy → hard
- 24 runnable Solidity snippets — Hardhat-compatible, OZ 5.x
git clone https://github.com/lopezpalacios/paycodex-onchain
cd paycodex-onchain
# Set up a Hardhat project
mkdir ../demo && cd ../demo
npm init -y
npm install --save-dev hardhat @nomicfoundation/hardhat-toolbox
npm install @openzeppelin/contracts
npx hardhat init # pick "Create a TypeScript project"
# Copy reference config + a snippet + sample test
cp ../paycodex-onchain/code/hardhat.config.ts hardhat.config.ts
cp ../paycodex-onchain/code/01-erc20-transfer.sol contracts/
cp ../paycodex-onchain/code/sample.test.ts test/
# Build + test
npx hardhat compile
npx hardhat testprompt.md — self-contained reusable prompt for spinning up DLT-strategist discussions with any AI assistant.
| Persona | Start here |
|---|---|
| DLT newcomer | 01-dlt-fundamentals.md → 02-evm-stack.md → use case 001 |
| Cash mgmt expert | 03-cash-legs-comparison.md → pick adjacent use case |
| Engineer | code/README.md → run snippets in Hardhat |
| Architect | 04-bank-integration-stack.md → architecture/bank-dlt-rail-pattern.md |
| Compliance | 05-compliance-stack.md → compliance/ |
| Strategist | prompt.md + EXECUTIVE-DECK.md |
EXECUTIVE-DECK.md — Marp-format slide deck. Render:
npm i -g @marp-team/marp-cli
marp EXECUTIVE-DECK.md --pptx -o exec.pptx01-dlt-fundamentals.md— what is DLT, advantages vs incumbent rails02-evm-stack.md— EVM, L1/L2/permissioned, tooling03-cash-legs-comparison.md— the four+1 types of money04-bank-integration-stack.md— SAP / Oracle / Temenos / Thought Machine / Mambu / Kyriba / Volante05-compliance-stack.md— Travel Rule, T-REX, MiCA, FINMA DLT, EU DLT Pilot
| Type | Issuer | Tier of money | Best for |
|---|---|---|---|
| Stablecoin (public) | Private EMI (regulated) | Tier 2 | DeFi treasury, FX, cross-border |
| Tokenized deposit | Licensed bank | Tier 2 | Interbank, in-house bank |
| Wholesale CBDC | Central bank | Tier 1 | DvP wholesale, interbank settlement |
| Retail CBDC | Central bank | Tier 1 | Retail consumer (when live) |
| Tokenized MMF | Asset manager | Investment | Idle cash yield |
paycodex-factory — runnable Hardhat project with the same snippets, TypeScript tests, gas reports, and GitHub Actions CI. Tested gas costs feed back into code/RESULTS.md.
paycodex-rules-poc — rule-driven interest-bearing deposit factory. Hardhat + AssemblyScript WASM (browser-runnable preview) + local Besu IBFT2 via Docker. 8 canonical interest rules (simple, compound, tiered, floating, KPI-linked, floor/cap, two-track ECR, CH withholding). WASM previews are parity-tested against the Solidity strategies. Implements [[architecture/programmable-interest-pattern]] + [[architecture/rule-driven-deployment-pattern]].
flowchart LR
KG1[paycodex<br/>incumbent rails KG] -->|references| Factory
KG2[paycodex-onchain<br/>EVM patterns KG<br/>this repo] -->|sources snippets| Factory[paycodex-factory<br/>Hardhat + TS + CI]
Factory -->|gas, coverage, test results| Feedback[(RESULTS.md)]
Feedback --> KG2
KG1 -->|rule schema| Rules[paycodex-rules-poc<br/>WASM + Solidity + Besu]
KG2 -->|patterns + ADRs| Rules
paycodex — incumbent CH/EU/UK rails (SCT Inst, SDD, QR-bill, CHAPS, FPS, T2S DvP, etc.). Every use case here cross-links to its incumbent equivalent there.
Solidity 0.8.20+ · Hardhat · TypeScript · ethers.js v6 · OpenZeppelin 5.x · Ethereum L1 + Base + Arbitrum + Polygon · Hyperledger Besu (permissioned) · Tokeny T-REX · Chainlink oracles · Notabene Travel Rule
See CONTRIBUTING.md.
- Code (Solidity, scripts) — MIT
- Documentation (markdown) — CC-BY-SA-4.0