21st SDK for Go

Go SDK for 21st Agents. Manage sandboxes, threads, and tokens programmatically.

Install

go get github.com/21st-dev/21st-sdk-go

Quick Start

package main

import (
	"context"
	"fmt"
	"log"

	agents "github.com/21st-dev/21st-sdk-go"
)

func main() {
	client := agents.NewAgentClient("an_sk_...") // your API key

	ctx := context.Background()

	// Create a sandbox for your agent
	sandbox, err := client.Sandboxes.Create(ctx, &agents.CreateSandboxRequest{
		Agent: "my-agent",
	})
	if err != nil {
		log.Fatal(err)
	}

	// Create a thread
	thread, err := client.Threads.Create(ctx, sandbox.ID, "Review PR #42")
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println("Thread:", thread.ID)

	// Generate a short-lived token for browser clients
	token, err := client.Tokens.Create(ctx, &agents.CreateTokenRequest{
		Agent:     "my-agent",
		ExpiresIn: "1h",
	})
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println("Token expires at:", token.ExpiresAt)
}

API

agents.NewAgentClient(apiKey, ...opts)

client := agents.NewAgentClient(
	"an_sk_...",                                       // API key (required)
	agents.WithBaseURL("https://custom-relay.example"), // optional
	agents.WithHTTPClient(customHTTPClient),            // optional
)

client.Sandboxes

Method	Description
Create(ctx, *CreateSandboxRequest)	Create a new sandbox for an agent
Get(ctx, sandboxID)	Get sandbox details (status, threads, agent info)
Delete(ctx, sandboxID)	Delete a sandbox
Exec(ctx, *ExecRequest)	Run a command in a sandbox

client.Sandboxes.Files

Method	Description
Write(ctx, sandboxID, files)	Write files to a sandbox
Read(ctx, sandboxID, path)	Read a file from a sandbox

client.Sandboxes.Git

Method	Description
Clone(ctx, sandboxID, *GitCloneRequest)	Clone a repository into a sandbox

client.Threads

Method	Description
List(ctx, sandboxID)	List all threads in a sandbox
Create(ctx, sandboxID, name)	Create a new thread
Get(ctx, sandboxID, threadID)	Get thread with messages
Delete(ctx, sandboxID, threadID)	Delete a thread
Run(ctx, *RunThreadRequest)	Send messages to an agent (streaming)

client.Tokens

Method	Description
Create(ctx, *CreateTokenRequest)	Create a short-lived JWT (default: 1h)

Error Handling

detail, err := client.Sandboxes.Get(ctx, "nonexistent")
if agents.IsAPIError(err, 404) {
	fmt.Println("sandbox not found")
}

License

MIT