SDKs

How the SDK relates to the API

eSign Launchpad's REST API at api.esignlaunchpad.com is the canonical interface. Every capability the platform offers is available via HTTPS and an OAuth 2.0 Authorization: Bearer header. You can integrate directly using any HTTP client in any language. See the authentication guide for the credential types and token flow.

The SDKs below are convenience wrappers auto-generated from the OpenAPI specification that backs the API. They do not add capabilities. Each SDK is a one-to-one mapping of API operations to idiomatic method calls in a given language, with typed request and response models. You get editor autocomplete and compile-time checks instead of writing raw JSON. Pick an SDK when you want your integration to read cleanly in the language you already write. Use the REST API directly when you need the thinnest possible dependency footprint or when your language is not listed below.

Every SDK regenerates each time the API spec changes, so the SDK is always a faithful mirror of what the live API accepts and returns.

Download source

Source zips are available for each language. Each zip contains a complete, buildable generated client (models, API classes, a README, and the language's native build file, for example csproj, package.json, pyproject.toml, pom.xml, go.mod, Gemfile, or composer.json). Drop the zip into your project, build locally, and you have a working client.

MCP server (for AI agents)

Alongside the language SDKs, eSign Launchpad ships a Model Context Protocol (MCP) server that lets AI agents like Claude, Cursor, and other MCP-aware tools call the API directly. It is the same set of operations as the SDKs, exposed as MCP tools so an agent can create a package, add signers, send for signature, check status, and download the result without you writing any wrapper code. The MCP server is published to npm as @esignlaunchpad/mcp-server and is the one component today that installs from a public registry.

Step 1 - Generate a credential

In your eSign Launchpad portal, go to Settings › API and click Generate. You can choose either credential type - the MCP server (v2.0.0 and later) auto-detects which format you provide and authenticates correctly:

• Personal Access Token (PAT) - a single long bearer string. Easiest for individual use; copy once and you're done. Used directly as Authorization: Bearer <token>.
• OAuth client credentials - a composite clientId:clientSecret string. The MCP server exchanges this at /connect/token for a 1-hour access token, caches it in process, and refreshes automatically before expiry. Pick this if your security posture requires short-lived access tokens at rest or if you want standards-compliant OAuth for compliance reviews.

Scope the credential to the permissions your agent needs. Typical agent setups want sign.package.read + sign.package.create + sign.package.send, optionally sign.template.read. The credential is shown only once - treat it like a production secret. See the authentication guide for the full background on credential types, scopes, and the underlying OAuth 2.0 flows.

Step 2 - Pick a launch mode

All examples below show the credential as <your_credential> - paste in either a PAT or an clientId:clientSecret string. The server detects the format on its own.

Option A. On-demand via npx (recommended for MCP clients)

No install step. Your MCP client spawns the server fresh each time it starts a session, so you always get the latest version that's been published.

ESIGN_API_KEY=<your_credential> npx -y @esignlaunchpad/mcp-server

Option B. Global install

Install once, then invoke the bin shim. Useful if you want a pinned version, faster startup, or to run the server outside an MCP client (for example, behind your own bridge process).

npm install -g @esignlaunchpad/mcp-server

# The package exposes an `esign-mcp` bin
ESIGN_API_KEY=<your_credential> esign-mcp

Option C. Local dev install

npm install @esignlaunchpad/mcp-server
ESIGN_API_KEY=<your_credential> npx esign-mcp

Step 3 - Wire it into your AI client

Claude Desktop

Open claude_desktop_config.json (~/Library/Application Support/Claude/claude_desktop_config.json on macOS, %APPDATA%\Claude\claude_desktop_config.json on Windows) and add an entry under mcpServers:

{
  "mcpServers": {
    "esign-launchpad": {
      "command": "npx",
      "args": ["-y", "@esignlaunchpad/mcp-server"],
      "env": {
        "ESIGN_API_KEY": "<your_credential>"
      }
    }
  }
}

Restart Claude Desktop. The eSign Launchpad tools appear in the tool picker.

Cursor

Open Cursor's MCP settings (Settings › Features › Model Context Protocol) and add an entry of type command:

{
  "mcpServers": {
    "esign-launchpad": {
      "command": "npx",
      "args": ["-y", "@esignlaunchpad/mcp-server"],
      "env": {
        "ESIGN_API_KEY": "<your_credential>"
      }
    }
  }
}

Other MCP-compatible clients

Any client that supports the standard command/args/env shape above will work. The server speaks MCP over stdio.

Environment variables

Verify it's working

Run the server directly from a terminal - if it starts cleanly and prints the API base URL it's reaching, your config is good:

ESIGN_API_KEY=<your_credential> npx -y @esignlaunchpad/mcp-server

The server listens on stdio, so you'll see the startup banner and then it will sit quietly waiting for an MCP client to connect. Ctrl-C to exit. From your MCP client, asking the agent "list my recent eSign packages" or "create a draft package called Test" is the fastest smoke test that the connection is live and the credential has the right scopes.

Upgrading from MCP server v1.x

If you installed the MCP server before v2.0.0, the ESIGN_API_KEY environment variable used to take a legacy static eslp_live_… API key and the server sent it as an X-API-KEY header. That auth path no longer exists on the server. Generate a fresh PAT or OAuth credential from Settings › API and replace the value of ESIGN_API_KEY. No other change is required - the env var name and config shape are unchanged.

Compiled packages for the language SDKs

The build pipeline also produces compiled artifacts for the languages with a native package format: .nupkg for C#, .tgz for TypeScript and Node.js, .whl for Python, and .jar for Java. The plan is to publish these directly to the standard package registries so they install with a single command:

• C#. NuGet. dotnet add package ESignLaunchpad.ApiClient
• TypeScript or Node.js. npm. npm install @esignlaunchpad/api-client
• Python. PyPI. pip install esignlaunchpad
• Java. Maven Central.

Using the SDKs

Each zip includes a language-specific README with a hello-world example. The browsable API reference in the left sidebar covers the method signatures and model shapes for every SDK, regardless of language, because all SDKs share the same underlying operations.