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.
- Real-time durable streaming is built in. Stream partial output, such as large language model (LLM) tokens and progress, to clients with streams that survive reconnects, cold starts, and replays. This durability supports 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, TypeScript, 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 and Durable Objects. Both replay; they handle versioning and encryption differently.
vs AWS Step Functions
Declarative ASL JSON state machines compared with 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 infrastructure over HTTP.
vs trigger.dev
A TypeScript task platform that achieves durability by snapshotting the process (CRIU).
Each deep dive includes a concept-mapping section for moving an existing system. The Workflow SDK migration skill can translate code for you:
npx skills add https://github.com/vercel/workflow --skill migrating-to-workflow-sdk