What is Reflow

Reflow is durable workflow execution for TypeScript. You define a multi-step operation — a signup, an import, an AI pipeline — as a chain of steps, and Reflow makes each step durable: persisted, retryable, and resumable after a crash. It runs on a SQLite file with no external services.

The problem

You have a multi-step operation. You write it as a normal async function:

app.post('/signup', async (req, res) => {
  await createAccount(req.body)     // ✅ done
  await chargeStripe(req.body)      // ✅ done
  // 💥 process crashes, deploy happens, laptop sleeps
  await sendWelcomeEmail(req.body)  // ❌ never runs
})

Now the user is charged but never got their welcome email — and you don't know which steps completed. Re-run everything and they get double-charged.

The usual fix is to hand-roll checkpoint logic: state columns, retry loops, deduplication. That's a few hundred lines of infrastructure that's hard to test and easy to get wrong.

Reflow makes each step durable instead. If the process crashes after step 2 of 5, a new engine instance reclaims the stale run once its lease expires and picks up at step 3. Active workers heartbeat their lease while they run, completed steps are never re-executed, and each step's output is persisted in SQLite.

Who is this for

Solo devs and small teams who need reliable multi-step workflows but don't want to run Temporal clusters or pay for cloud workflow services.

• AI pipelines — LLM calls cost money; don't re-run a $0.05 call because the next step failed.
• SaaS apps — background jobs that must complete: signup flows, billing, provisioning.
• CLI tools — long-running imports or migrations that should resume after interruption.

Don't use Reflow when:

• You need distributed execution across multiple machines.
• You need sub-second latency on workflow dispatch.
• You're already running Temporal or similar.

How it compares

	Reflow	Temporal	Inngest
Infrastructure	None (SQLite file)	Temporal Server + DB	Cloud service
Type safety	Full end-to-end	Partial	Partial
Setup	bun add reflow-ts	Cluster deployment	Account + SDK
Best for	Single-process apps, CLIs, AI agents	Large distributed systems	Serverless

Next steps

• Installation — add Reflow and pick a storage adapter.
• Quick Start — define and run your first workflow.
• Workflows — the building blocks: steps, prev, steps, and the immutable builder.