API Keys

LangWatch uses API keys to authenticate SDK calls, MCP connections, and API requests. All keys are managed from a single place: Settings → API Keys.

Ingestion keys vs API keys

LangWatch splits credentials into two concepts, the same way Datadog separates ingest-only API keys from RBAC-scoped application keys. Both are sk-lw-… strings, but they carry very different power:

	Ingestion key	API key
What it does	Writes traces, and nothing else	Reads and manages everything its scope allows
Role	A built-in, write-only ingest-only role granting only `traces:create`	RBAC scopes you pick (personal: your ceiling; service: scope + mode)
Scope	Exactly one project	One or more projects, teams, or the whole organization
Best for	Spraying into agent environments, CLIs, and OTLP exporters (Claude Code, Cursor, Claude cowork, …) where you only want to push telemetry	SDK setup, MCP, CI/CD, dashboards, automation, anything that reads or changes data
Blast radius if leaked	Minimal, it can only create traces in its one project, never read or delete	Whatever its RBAC scope grants, treat it like a password

Because an ingestion key is genuinely write-only, it’s safe to drop into an agent’s environment or a managed-settings file. An ingestion template mints one for you and wires it into the tool’s OTEL_EXPORTER_OTLP_HEADERS; the langwatch <tool> CLI does the same on your behalf. An ingestion key may also reference an IngestionTemplate (its OTTL / catalog metadata) so the receiver shapes the trace into the canonical gen_ai.* form. The rest of this page covers the RBAC-scoped API keys you create from Settings → API Keys.

Key Types

	Personal Key	Service Key
Tied to	A specific user	No user (org-level)
Best for	Local development, AI assistants (MCP), personal workflows	CI/CD pipelines, automation, service-to-service
Permissions	Inherits your RBAC permissions (ceiling model)	Scoped to specific projects with ADMIN access
Survives user removal	No — disabled when user leaves the org	Yes — independent of any user
Requires `LANGWATCH_PROJECT_ID`	Yes	Yes

Legacy project keys (the LANGWATCH_API_KEY shown on the project setup page) still work and will continue to be supported. They have the project context built in, so they don’t require LANGWATCH_PROJECT_ID. New users should prefer creating keys from Settings → API Keys for better security and access control.

Creating a Personal API Key

Personal keys are ideal for local development, connecting your AI coding assistant via MCP, or any workflow where you want the key tied to your identity.

Go to Settings → API Keys

Navigate to Settings → API Keys in your LangWatch dashboard.

Click Create API Key

Click the Create API Key button in the top right.

Configure the key

Type: Select Personal
Name: Give it a descriptive name (e.g., “My MCP key”, “Local dev”)
Scope: Select which projects, teams, or the whole organization the key can access
Expiration: Optionally set an expiration date
Permissions: Choose a permission mode:
- All — inherits your full permissions at each scope
- Restricted — fine-grained control over individual permission categories (see Permission Categories)

Copy your key

After creation, your key is shown once. Copy it and store it securely — you won’t be able to see the full key again.The key format is: sk-lw-<id>_<secret>

Using a Personal Key

Set both LANGWATCH_API_KEY and LANGWATCH_PROJECT_ID in your environment:

.env

LANGWATCH_API_KEY="sk-lw-..."
LANGWATCH_PROJECT_ID="your-project-id"

You can find your project ID in Settings → Projects or in the project URL.

Creating a Service API Key

Service keys are designed for automated systems — CI/CD pipelines, production services, and multi-project setups. They aren’t tied to any user, so they keep working even if team members leave.

Only organization admins can create service keys.

Go to Settings → API Keys

Navigate to Settings → API Keys in your LangWatch dashboard.

Click Create API Key

Click the Create API Key button in the top right.

Configure the key

Type: Select Service
Name: Give it a descriptive name (e.g., “CI pipeline”, “Production tracing”)
Scope: Select which projects, teams, or the whole organization the key can access
Expiration: Optionally set an expiration date
Permissions: Choose All for full access, or Restricted for fine-grained control

A service key scoped to the organization with All permissions gets org-wide ADMIN access. Always scope to specific projects when possible.

Copy your key

After creation, your key is shown once. Copy it and store it securely.

Using a Service Key

Service keys require LANGWATCH_PROJECT_ID so the SDK knows which project to send traces to:

Environment variables
Python
TypeScript

.env

LANGWATCH_API_KEY="sk-lw-..."
LANGWATCH_PROJECT_ID="your-project-id"

import langwatch

langwatch.setup(
    api_key="sk-lw-...",
    project_id="your-project-id",
)

import { LangWatch } from 'langwatch';

const langwatch = new LangWatch({
  apiKey: 'sk-lw-...',
  projectId: 'your-project-id',
});

Permission Categories

When using Restricted permissions, you can grant read or write access to individual feature areas:

Category	Read	Write
Traces	View traces and spans	Create, update, and share traces
Cost	View cost analytics	—
Scenarios	View test scenarios	Create and manage scenarios
Annotations	View annotations	Create and manage annotations
Analytics	View analytics dashboards	Create and manage dashboards
Evaluations	View evaluations	Create and manage evaluations
Datasets	View datasets	Create and manage datasets
Triggers	View triggers	Create and manage triggers
Workflows	View workflows	Create and manage workflows
Prompts	View prompts	Create and manage prompts
Secrets	View secrets	Create and manage secrets
Audit Log	View audit log	—
Team	View team members	Manage team membership
Project	View project settings	Create, update, and delete projects

Categories marked with ”—” for write are read-only by design.

Connecting to AI Assistants (MCP)

Personal API keys work with the LangWatch MCP Server to give your AI coding assistant access to LangWatch features — tracing, analytics, prompt management, and more.

Create a personal API key

Follow the steps above to create a personal key.

Add the MCP server to your editor

Claude Code
Cursor / VS Code

claude mcp add langwatch -- npx -y @langwatch/mcp-server --apiKey sk-lw-...

{
  "mcpServers": {
    "langwatch": {
      "command": "npx",
      "args": ["-y", "@langwatch/mcp-server"],
      "env": {
        "LANGWATCH_API_KEY": "sk-lw-..."
      }
    }
  }
}

See the full MCP setup guide for all supported editors.

Ask your assistant to instrument your code

"Instrument my codebase with LangWatch"

Permissions Model

API key permissions follow a ceiling model: a personal key can never exceed the creating user’s own permissions.

If you have ADMIN access and create a key with All permissions, the key gets ADMIN
If you have MEMBER access and create a key with All permissions, the key gets MEMBER (not ADMIN)
Restricted keys let you manually narrow access to specific permission categories at read or write level

Service keys bypass the user ceiling since they have no associated user — their permissions come directly from their scope and permission mode. For more on roles and permissions, see Access Control (RBAC).

Managing Keys

From the Settings → API Keys page you can:

View all keys — see name, type, status, scope, permissions, creation date, last used, and creator
Edit a key — update the name, permission mode, or permission categories
Revoke a key — immediately disables the key (cannot be undone)

Rotate keys regularly and revoke any that are no longer in use. Set expiration dates on keys used for temporary workflows.

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Help

Ingestion keys vs API keys

Key Types

Creating a Personal API Key

Using a Personal Key

Creating a Service API Key

Using a Service Key

Permission Categories

Connecting to AI Assistants (MCP)

Permissions Model

Managing Keys

​Ingestion keys vs API keys

​Key Types

​Creating a Personal API Key

​Using a Personal Key

​Creating a Service API Key

​Using a Service Key

​Permission Categories

​Connecting to AI Assistants (MCP)

​Permissions Model

​Managing Keys

Ingestion keys vs API keys

Key Types

Creating a Personal API Key

Using a Personal Key

Creating a Service API Key

Using a Service Key

Permission Categories

Connecting to AI Assistants (MCP)

Permissions Model

Managing Keys