Your Modular AI Stack

Your Modular
AI Stack

Loopstack is a TypeScript framework based on NestJS for building AI agents and durable AI workflows.

Open SourceTypeScriptNestJSStudio & CLI

const { workflowId } = await this.workflowRunner.run(
  ReviewTicketWorkflow,
  { ticketId },
);

What You Build

Build stateful AI agents and workflows that call your tools, coordinate sub-agents, and pause for human input.

Knowledge retrieval
Research & summarization
Data analysis
Fact-checking
Coding automation
Content & doc pipelines
Agent harness

How It Works

Compose complex AI systems from modular building blocks

@Workflow()
export class MyWorkflow extends BaseWorkflow {
  // inject any service or tool here

  @Transition({ from: 'start', to: 'step1done' })
  async handleStep1(state, ctx) {
    // any code for step 1
  }

  @Transition({ from: 'step1done', to: 'end' })
  async handleStep2(state, ctx) {
    // any code for step 2
  }
}

Workflows

Workflows are TypeScript state machines with explicit states and transitions. Inject tools, call LLMs, and create structured documents within transitions. Take different paths depending on the result, run steps in parallel, or pause for a human to respond. A single step can run another workflow or an AI agent. Every step is checkpointed, so failures resume right where they left off.

Learn more

@Tool()
export class MyCustomTool extends BaseTool {
  async handle(args, ctx) {
    // any code for the tool
    return { data: result };
  }
}

Tools

Tools are injectable NestJS services with Zod-validated inputs. Use them in workflows for deterministic steps, or expose them to LLMs so agents can decide when to call them. Build your own or install ready-made ones from the registry.

Learn more

@Document({ schema: ClassificationSchema })
export class MyClassificationDocument {
  priority: 'urgent' | 'high' | 'medium' | 'low';
  summary: string;
}

Documents

Documents are typed data objects that bridge your workflow and the UI. Define a Zod schema and they render automatically as forms, messages, or structured output in the Loopstack Studio. Users interact with documents to provide approvals, fill in data, or review AI-generated results.

Learn more

@Module({
  imports: [ClaudeModule, AgentModule],
  providers: [MyWorkflow, MyCustomTool],
})
export class MyModule {}

Modules

A module is a standard NestJS module. It imports feature modules like LLM providers or agents, and registers your tools and workflows as providers via standard dependency injection.

Learn more

Integrate into your app

Trigger workflows from anywhere in your NestJS app: a controller, a queue consumer, or a scheduled job.

Run via Cron, webhooks, queues, or any service
Subscribe to streamed output
Hand off to browser interface

Learn more about programmatic execution

@Cron(CronExpression.EVERY_30_MINUTES)
async sweepStaleTickets() {

  const { workflowId } = await this.workflowRunner.run(
    TriageTicketWorkflow,
    { status: 'stale' },
  );

}

Two ways to drive a run

Start a workflow, follow it live, and answer its prompts — from the terminal or the browser. Both ship with the framework.

CLI

npm i -g @loopstack/cli — and every workflow is a command. Runs stream live: transitions, LLM tokens, tool calls, and human-in-the-loop prompts answered right in your terminal.

CI-ready with JSON output & exit codes
Operable by AI agents
Attach to any running workflow

Explore the CLI reference

Studio

Run, debug, and organize automations in the built-in frontend. Forms, documents, and live progress render from your workflow's config — no frontend code required.