> ## Documentation Index
> Fetch the complete documentation index at: https://docs.truthlocks.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Manage add-ons

> Attach or detach add-ons to extend your plan with additional features and quotas.

Add-ons let you extend your plan with extra capabilities — additional seats, priority SLA, a private transparency log, and more. See the [billing overview](/billing/overview#add-ons) for the full add-on catalog.

## Attach an add-on

```http theme={null}
POST /v1/billing/addons/attach
```

Attaches an add-on to your tenant. If the add-on has a price, the response includes a `checkout_url` to complete payment. Free add-ons activate immediately.

### Request body

<ParamField body="addon_key" type="string" required>
  The add-on identifier. See the table below for available keys.
</ParamField>

<ParamField body="quantity" type="integer">
  Number of units to attach. Defaults to `1`. For example, set `quantity` to `3` for three extra seats.
</ParamField>

### Response

<ResponseField name="checkout_url" type="string">
  Payment URL if the add-on requires payment. Redirect the user to complete checkout. Not included for free add-ons.
</ResponseField>

<ResponseField name="status" type="string">
  `active` for free add-ons, `pending_payment` when a checkout is required.
</ResponseField>

***

## Detach an add-on

```http theme={null}
POST /v1/billing/addons/detach
```

Removes an add-on from your tenant. The associated entitlements are removed at the end of the current billing period.

### Request body

<ParamField body="addon_key" type="string" required>
  The add-on identifier to remove.
</ParamField>

***

## Available add-ons

| Key                  | Name               | Description                                             |
| :------------------- | :----------------- | :------------------------------------------------------ |
| `addon_seat`         | Extra Seats        | +1 team member per unit beyond your plan limit          |
| `addon_sla_priority` | Priority SLA       | Guaranteed response times for support                   |
| `addon_private_log`  | Private Log        | Dedicated transparency log instance                     |
| `addon_compliance`   | Compliance Pack    | SOC 2 reports and regulatory compliance bundle          |
| `addon_whitelabel`   | White-Label        | Remove Truthlocks branding from badges and certificates |
| `addon_ratelimit`    | Rate Limit Boost   | 10x API rate limit multiplier                           |
| `addon_retention`    | Extended Retention | Longer data and audit log retention periods             |

<Tip>
  Check your current add-ons and resolved entitlements with the [entitlements endpoint](/api-reference/billing/entitlements). Add-on quotas are automatically merged into your plan quotas.
</Tip>


## OpenAPI

````yaml mint-openapi.yaml POST /v1/billing/addons/attach
openapi: 3.0.3
info:
  title: Truthlocks API
  description: >
    Truthlocks is a universal verification infrastructure for documents,
    credentials, and digital assets.

    This specification defines the canonical API for interacting with Truthlocks
    services.


    ## Base URLs

    - **Production**: `https://api.truthlocks.com`

    - **Sandbox**: `https://sandbox-api.truthlocks.com`


    ## Authentication

    - **API Keys**: Use `X-API-Key` header for machine-to-machine operations

    - **Bearer Tokens**: Use `Authorization: Bearer <jwt>` for user-initiated
    operations


    ## Tenant Identity

    In production, tenant identity is derived from the authenticated context
    (API key or JWT).

    The `X-Tenant-ID` header is ignored in production to prevent spoofing.
  version: 1.0.0
  contact:
    name: Truthlocks Support
    url: https://truthlocks.com/support
    email: support@truthlocks.com
servers:
  - url: https://api.truthlocks.com
    description: Production API
  - url: https://sandbox-api.truthlocks.com
    description: Sandbox Environment
security:
  - APIKey: []
tags:
  - name: Authentication
    description: API key and token management
  - name: Issuers
    description: Issuer registration and trust management
  - name: Keys
    description: Cryptographic key management for issuers
  - name: Attestations
    description: Attestation lifecycle (mint, revoke, supersede)
  - name: Verification
    description: Attestation verification and proof bundles
  - name: Governance
    description: Issuer governance workflows (admin only)
  - name: Identity
    description: Organization, user, and role management
  - name: Audit
    description: Audit event queries
  - name: Platform
    description: Platform administration (super admin only)
  - name: Platform Review
    description: Staff review workflows for issuer applications
  - name: Tenant Console
    description: Tenant profile and lifecycle endpoints
  - name: Health
    description: Service health and readiness endpoints
  - name: Risk
    description: Risk signal ingestion and fraud detection
  - name: Risk Enforcement
    description: Risk enforcement actions — block, challenge, quarantine, and configuration
  - name: Billing
    description: Billing, subscription, and addon management
  - name: Machine Identity
    description: >-
      Machine Agent Identity Protocol (MAIP) — agent registration, sessions,
      trust, witness, compliance, orchestration, and observability
externalDocs:
  description: Transparency read-only API (separate service spec)
  url: >-
    https://github.com/truthlocks/truthlock/blob/main/docs/transparency/openapi.yaml
paths:
  /v1/billing/addons/attach:
    post:
      tags:
        - Billing
      summary: Attach addon
      description: Attaches a billing addon to the tenant's subscription.
      operationId: billing.addons.attach
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              required:
                - addon_id
              properties:
                addon_id:
                  type: string
                  description: Addon identifier to attach
                quantity:
                  type: integer
                  description: Number of addon units
      responses:
        '200':
          description: Addon attached
          content:
            application/json:
              schema:
                type: object
                properties:
                  addon_id:
                    type: string
                  status:
                    type: string
                  effective_at:
                    type: string
        '401':
          description: Authentication required
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorEnvelope'
      security:
        - APIKey: []
components:
  schemas:
    ErrorEnvelope:
      type: object
      required:
        - code
        - message
        - http_status
      properties:
        code:
          type: string
          description: Machine-readable error code
          enum:
            - AUTH_REQUIRED
            - AUTH_INVALID
            - PERMISSION_DENIED
            - TENANT_IDENTITY_UNVERIFIED
            - NOT_FOUND
            - VALIDATION_ERROR
            - CONFLICT
            - PAYLOAD_TOO_LARGE
            - RATE_LIMIT_EXCEEDED
            - QUOTA_EXCEEDED
            - SERVICE_UNAVAILABLE
            - INTERNAL_ERROR
        message:
          type: string
          description: Human-readable error message
        http_status:
          type: integer
          description: HTTP status code
        retry_after_ms:
          type: integer
          description: Milliseconds to wait before retrying (for rate limits)
        details:
          type: object
          description: Additional error context
      example:
        code: AUTH_REQUIRED
        message: Authentication required
        http_status: 401
  securitySchemes:
    APIKey:
      type: apiKey
      in: header
      name: X-API-Key
      description: API key for machine-to-machine authentication

````