Runtime SDKs

The Swytchcode Runtime SDKs allow you to execute trusted tools directly from your application without interacting with the CLI manually.

Whether you’re building an AI agent, backend service, workflow automation, or developer tool, the Runtime SDK provides a simple API for executing tools while letting Swytchcode handle authentication, policies, retries, and API execution.

Instead of writing provider-specific SDK code, you simply execute a trusted tool.

Under the hood, the SDK doesn’t reimplement any of this logic - it calls into the same execution engine that powers swy exec from the CLI. As the CLI overview puts it: “even if you’re building a custom AI application with the JavaScript or Python Runtime SDK, the CLI remains the underlying execution engine.” Your project’s tooling.json, manifest.json, and policies.json are read the same way regardless of whether the request came from a terminal command, an MCP client, or a line of application code.

Why Runtime SDKs?

Without a runtime SDK, applications typically need to:

Build HTTP requests manually
Manage API authentication
Handle retries and timeouts
Implement idempotency
Validate request inputs
Execute provider-specific SDKs
Handle provider-specific error responses

The Runtime SDK removes this complexity by delegating execution to the Swytchcode runtime.

Your Application
        │
        ▼
Runtime SDK
        │
        ▼
Swytchcode Runtime
        │
        ▼
Provider API

This provides a consistent execution model regardless of which provider your application interacts with.

How It Works

Every SDK follows the same execution pipeline.

Application
      │
      ▼
Execute Tool
      │
      ▼
Input Validation
      │
      ▼
Policy Evaluation
      │
      ▼
Authentication
      │
      ▼
Execution Policy
      │
      ▼
Provider API
      │
      ▼
Return Response

The Runtime SDK is responsible for invoking the Swytchcode runtime, while the runtime itself performs validation, authentication, policy evaluation, retries, and API execution. This is the same execution path documented in the CLI’s Execution lifecycle - the SDK is a language-native entry point into it, not a separate implementation.

Supported Runtime SDKs

Swytchcode currently provides Runtime SDKs for the following languages.

SDK	Status
JavaScript	✅ Supported
Python	✅ Supported
Go	🚧 Coming Soon

Each SDK exposes an idiomatic interface for its language while sharing the same execution model.

The runtime SDK documentation includes separate guides for JavaScript runtime and Python runtime, as well as the shared Execution Pipeline guide.

Common Features

Every Runtime SDK includes the same core capabilities.

Execute Trusted Tools

Execute any method or workflow that has been enabled in your project. See the Execution Pipeline for examples and best practices.

Automatic Authentication

Provider credentials are resolved automatically before execution.

No additional authentication logic is required in your application. See Managed Authentication to learn how credentials are resolved and stored.

Policy Enforcement

Every request is evaluated against your project’s policies before reaching the provider. Learn how policies protect execution in Policies & Guardrails.

Production-Ready Execution

Execution policies defined in manifest.json are applied automatically, including:

Retries
Timeouts
Idempotency
Concurrency limits

Consistent Responses

The runtime normalizes responses and errors, providing a predictable developer experience across different providers.

When Should You Use the Runtime SDK?

The Runtime SDK is ideal for:

AI agents
Backend services
Serverless functions
Internal developer tools
Workflow automation
Production applications

If your application needs to execute Swytchcode tools programmatically, the Runtime SDK is the recommended integration.

Runtime SDK vs CLI

Both interfaces execute through the same CLI-powered engine - the SDK doesn’t bypass the CLI, it calls into the same code path that swy exec uses.

Runtime SDK	CLI
Embedded inside your application	Used from the terminal
Language-native API	Command-line interface
Best for production applications	Best for development and automation
Executes tools programmatically	Executes tools manually

Regardless of how execution begins, every request follows the same execution pipeline, reads the same tooling.json/manifest.json/policies.json project state, and is subject to the same policies.

Runtime Architecture

                  Your Application
                         │
             ┌───────────┴───────────┐
             │                       │
             ▼                       ▼
     JavaScript SDK           Python SDK
             │                       │
             └───────────┬───────────┘
                         │
                         ▼
                Swytchcode Runtime
                         │
        ┌────────────────┼────────────────┐
        │                │                │
        ▼                ▼                ▼
   Authentication   Policies      Execution Policy
                         │
                         ▼
                    Provider APIs

This shared architecture ensures consistent behavior across every supported language.

Choosing a Runtime

Choose the SDK that matches your application.

JavaScript SDK - Recommended for Node.js, Bun, Next.js, and serverless applications.
Python SDK - Recommended for AI agents, automation, data pipelines, and backend services.

Regardless of the language, every Runtime SDK executes tools using the same Swytchcode runtime.

Continue with:

Next Steps

JavaScript SDK

Learn how to install and use the runtime in Node.js applications.

Python SDK

Execute Swytchcode tools from Python.

Execution Pipeline

Understand how requests flow through validation, authentication, policies, and execution.

Authentication

Learn how credentials are resolved automatically when the runtime executes tools.