// the find
blnkfinance/blnk
Blnk is an open-source ledger & financial core for shipping fintech products fast.
Blnk is a Go service that runs a double-entry ledger on Postgres. It handles balances, inflight and scheduled transactions, reconciliation against external statements, and tokenized identities linked to balances. It is aimed at teams building wallets, payments, lending, or loyalty products who would rather self-host a ledger than write one.
- Tamper evidence is built in. There is a chain worker and a verify_chain command under cmd/, so you can check that past entries have not been altered. Most hobby ledgers skip this.
- The hard ledger cases have their own code and tests: inflight commit and void (transaction_inflight.go with async and bulk tests), dry-run parity between single and bulk transactions, and refunds. The parity tests suggest someone looked at the gap between preview and execution.
- Tests live next to almost every package, including an invariant fuzz test in model/ and k6 load scripts in tests/loadtest. That is a better signal than a badge.
- Apache 2.0 with docker-compose and Kubernetes manifests in the repo, so self-hosting is a real path and not just a README claim.
- The README is mostly a funnel. Nearly every section links to docs, Blnk Cloud, or paid support with UTM parameters. There is no schema, no example transaction, and no statement of what the ledger guarantees under concurrent writes or which isolation level it relies on. You learn what it is for, not whether it is correct.
- The open-core line is unclear. Reconciliation, identity tokenization, and support are presented as features, but the README does not say which ones are fully in the Apache-licensed code and which depend on Cloud or a support plan. Check that before you build on it.
- The operational footprint is large for a ledger. The Kubernetes manifests show Postgres, Redis, Typesense, Prometheus, and Jaeger alongside the server and workers. Typesense for search is a dependency you have to justify and keep in sync with the source of truth.