Comparisons
How the Workflow SDK compares to other durable execution, workflow, and AI-agent frameworks — Temporal, Cloudflare Workflows, AWS Step Functions, AWS Bedrock AgentCore, Inngest, and trigger.dev.
The Workflow SDK overlaps with several categories: durable execution engines, background-job platforms, managed orchestrators, and AI-agent runtimes. This section compares it against the most common alternatives, one deep dive per tool.
What makes the Workflow SDK different
- It's an open-source SDK, not a hosted product. Your workflows are plain TypeScript in your existing app. Run them on the managed Vercel World, or self-host on the Postgres World — the World abstraction lets you own and swap the storage, queue, and streaming layers independently.
- Versioning is safe by default. Runs are pinned to the immutable deployment that started them, so shipping new code never disturbs in-flight runs. Upgrading a run is explicit and opt-in. See Versioning.
- Realtime durable streaming is built in. Stream partial output (LLM tokens, progress) to clients with streams that survive reconnects, cold starts, and replays — essential for chat and agent UIs.
- First-class AI agents.
WorkflowAgentships inside the AI SDK, turning an agent loop into a durable workflow with automatic step retries and human-in-the-loop pauses.
Snapshot
These comparisons are compiled from each product's public documentation and are not based on head-to-head benchmarks — durable engines differ enough that a single number rarely compares cleanly. Treat them as directional and verify current pricing and limits against each vendor's docs.
| Tool | Category | Durability model | Open source / self-host | Language(s) |
|---|---|---|---|---|
| Workflow SDK | Durable functions SDK | Event-log + deterministic replay | ✅ Apache-2.0 — self-host (Postgres) or Vercel | TypeScript (Python beta) |
| Temporal | Durable execution platform | Event-sourced replay | ✅ MIT server — self-host or Temporal Cloud | Go, Java, TS, Python, .NET, PHP, Ruby |
| Cloudflare Workflows | Durable execution engine | Step-result memoization + replay | ❌ Cloudflare-only | TypeScript (Python beta) |
| AWS Step Functions | Managed state-machine orchestrator | Declarative ASL state machine | ❌ AWS-only | ASL JSON (tasks: any language) |
| AWS Bedrock AgentCore | AI-agent hosting platform | Not durable execution (ephemeral sessions) | ❌ AWS-only | Python, Node.js |
| Inngest | Durable functions / event platform | Step-result memoization | ◑ SSPL — self-host (community/best-effort) or SaaS | TypeScript (Python/Go pre-1.0) |
| trigger.dev | Durable task platform | Process checkpoint/restore (CRIU) | ✅ Apache-2.0 — self-host or Cloud | TypeScript only |
Deep dives
vs Temporal
The mature, language-agnostic durable-execution platform. You run the workers; Workflow SDK runs in your app.
vs Cloudflare Workflows
A durable engine on Workers + Durable Objects. Both replay; they handle versioning and encryption very differently.
vs AWS Step Functions
Declarative ASL JSON state machines vs. plain TypeScript control flow.
vs AWS Bedrock AgentCore
An AI-agent hosting platform — not a durable-execution engine. Different axis.
vs Inngest
Event-driven durable functions that run on your own infra over HTTP.
vs trigger.dev
A TypeScript task platform that achieves durability by snapshotting the process (CRIU).
Moving an existing system over? Each deep dive includes a concept-mapping section, and the Workflow SDK migration skill can translate code for you:
npx skills add https://github.com/vercel/workflow --skill migrating-to-workflow-sdk