# PART 2: Existing subsystems to reuse instead of building be… (1)

Checks 1 to 4 of 5, each with its evidence

## What you can do here

- **Verify 1: TigerBeetle | A purpose-built financial tra…**: Verify: TigerBeetle | A purpose-built financial transactions database (debits…
- **Verify 2: Formance Ledger | Programmable double-entry…**: Verify: Formance Ledger | Programmable double-entry ledger with the Numscript…
- **Verify 3: Formance Stack | Bundle: Ledger, Payments,…**: Verify: Formance Stack | Bundle: Ledger, Payments, Numscript and more | MIT f…
- **Verify 4: Blnk | Open-source double-entry ledger with…**: Verify: Blnk | Open-source double-entry ledger with balances, reconciliation…
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- **Open Meet the research: 2.1 Ledgers: evidence**