OpenAPI Describes Each Call. Arazzo Describes the API Workflow.
You've probably scripted your API workflow by hand, and it breaks quietly when the API changes. Write it as an Arazzo document instead. UseArazzo validates it, runs it against live APIs, and shows you exactly what happened at each step.
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Works with
Arazzo Specification
OpenAPI Specification (source descriptions)
Why API workflows still get improvised
Even with an OpenAPI description in hand, agent frameworks still improvise the call order at runtime, and improvisation is exactly what you don't want in production.
Read why it still happens →
What it does
Plenty of tools will tell you whether an Arazzo document is well formed. Far fewer will run it. UseArazzo does both, and tells you what happened.
Validate
The document, against the Arazzo specification. Every violation, with the location that caused it.
Run
The workflow, against live APIs described by your OpenAPI source descriptions.
Read the trace
Each step in run order: whether it succeeded, which action was selected, and how many attempts it took, alongside the workflow's outputs and final status.
None of it is installable yet. The Validator, the Runner, and the CLI are all under heavy development in the open, ahead of a first npm release.
Why UseArazzo
As maintainers of UseArazzo, we believe multi-step API workflows deserve the same rigor OpenAPI brought to single endpoints: described once, in a standard, and executed the same way every time. That's what Arazzo is for, and UseArazzo exists to validate and run it: deterministically, on your machine, in CI, or through an agent. It's one shared engine, not three separate tools that happen to sound related.
Deterministic execution
A workflow that ran yesterday runs the same today. Agents can choose which workflow to run, not improvise the steps inside it.
The standard is the product
We implement Arazzo exactly as the specification defines it. When something needs fixing, we fix it in the specification by contributing upstream, instead of adding private extensions that only our tools can read.
Portable artifacts
Plain Arazzo documents in your repository, driven from your own code, your CI pipeline, or an agent. If you stop using the toolkit, your API workflows keep working.
Validate and run workflows
The entire toolkit, CLI and Validator and Runner alike, is pre-1.0 and in heavy development. Nothing is published to npm yet, and APIs may change without notice. Everything below is built in the open, so you can read the code, follow along, and tell exactly where each piece stands.
CLI
One command-line interface across the toolchain: validate and run workflows on your machine and in CI. It will wrap the Validator and the Runner in a single binary.
- ✓
validate&runin one tool - ✓ CI-friendly exit codes
- ✓ Same engine as the libraries
- ☐ Not yet published to npm
Validator
Every violation against the Arazzo specification, pinned to the exact place in the document that caused it.
- ✓ Semantic validation & linting
- ✓ LSP-compatible diagnostics
- ✓ Opt-in JSON Schema validation
- ☐ Not yet published to npm
Runner
Executes workflows step by step: criteria evaluation, output mapping, failure actions, and retries, returning a per-step record of the run.
- ✓ Full control-flow (goto/retry/end)
- ✓ Sub-workflows &
dependsOn - ✓ Pluggable HTTP transport
- ☐ Not yet published to npm
Compatibility
What the toolkit can validate and run today.
| Document | Versions | Validate | Run |
|---|---|---|---|
| Workflow Document: Arazzo | 1.0.0, 1.0.1, 1.1.0 | ✓ Yes | ✓ Yes |
| Source Description: OpenAPI | 2.0, 3.0.x, 3.1.x | ✓ Yes | ✓ Yes |
| Source Description: OpenAPI | 3.2.x | ✗ No | ✗ No |
| Source Description: Arazzo | 1.0.0, 1.0.1, 1.1.0 | ✓ Yes | ✓ Yes |
| Source Description: AsyncAPI | any | ✗ No | ✗ No |
On the roadmap
None of this is built yet. It's where the toolkit is headed, published here so you can tell what exists today from what doesn't.
Language Service
An LSP-compatible library bringing Arazzo intelligence to any editor or tool: validation, completion, hover, go-to-definition, and find references.
Editor
A browser-based editor for authoring and validating Arazzo workflows with real-time feedback.
VS Code Extension
Arazzo authoring inside VS Code: real-time validation, semantic linting, autocompletion, and live preview.
GitHub Actions
Validation and run results reported where the work happens: violations annotated on the diff, the step-by-step run trace rendered into the job summary, and the check status driven by step outcomes rather than a single pass or fail.
Agent Skills
A set of task-shaped skills teaching agents to work the toolchain: authoring workflows from an API description, validating and fixing them, and reading a run trace when a step fails.
MCP Server
A generic Model Context Protocol server exposing validation and execution over any Arazzo document, so agents can check and run workflows with no build step.
MCP Compiler
Compiles a specific workflow into a dedicated MCP server: one typed tool per workflow, with real input schemas, for production agent deployments.
Arazzo Transformers
Explicit, versioned transformations for reshaping data between steps, declared as ordinary API calls the toolchain can validate rather than arbitrary code that needs a sandbox to run.
Get help from the maintainers
UseArazzo is free and open source. If you have a question, an idea, or a bug to report, Discussions is a good place to start, and you are welcome to email the maintainers directly about anything else.