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

# Top up balance

> Returns a link the user can visit to top up their balance. 

This is typically used when a request is rejected due to insufficient funds.




## OpenAPI

````yaml GET /user/balance/topup
openapi: 3.1.0
info:
  title: Paywalls.ai API
  description: >
    The Paywalls.ai API enables developers to integrate monetization and access
    control for OpenAI-compatible LLMs.


    This proxy service supports multiple pricing strategies—including
    per-request, token-based, and subscription models—while maintaining full
    compatibility with the OpenAI API format.


    Requests are automatically checked for user authorization and balance. If
    the user is not connected to the paywall, or lacks sufficient balance, the
    API will return actionable links for onboarding or top-up.


    Use this API to monetize your AI-powered apps and services with minimal
    effort.


    Visit [paywalls.ai](https://docs.paywalls.ai) for full documentation and
    setup guides.
  version: 1.0.0
servers:
  - url: https://api.paywalls.ai/v1
    description: Primary production server
security:
  - ApiKeyAuth: []
tags:
  - name: Chat
    description: >
      OpenAI-compatible chat completion endpoint that enforces paywall logic
      before proxying the request to a model provider.


      Automatically checks user connection, balance, and performs charging.
      Supports streaming and non-streaming completions.
  - name: Models
    description: >
      Retrieve metadata and pricing information about the LLM models supported
      by the proxy.


      Includes prompt and completion pricing, per-request costs, and display
      details for UI integration.
  - name: User
    description: >
      Endpoints for managing user sessions, balance, and charging status.


      Includes functionality for connecting to or disconnecting from the
      paywall, checking balance, initiating top-ups, and issuing manual charges.
  - name: Webhooks
    description: >
      Manage webhook subscriptions and inspect delivery activity for your
      paywall integrations.
paths:
  /user/balance/topup:
    get:
      tags:
        - User
      summary: Get a top-up link for adding user funds
      description: >
        Returns a link the user can visit to top up their balance. 


        This is typically used when a request is rejected due to insufficient
        funds.
      parameters:
        - $ref: '#/components/parameters/XPaywallUser'
        - in: query
          name: user
          required: false
          description: The unique identifier of the user to get top-up link for.
          schema:
            type: string
      responses:
        '200':
          description: successful operation
          content:
            application/json:
              schema:
                type: object
                properties:
                  url:
                    type: string
                    description: >-
                      The URL to redirect the user to for topping up their
                      balance.
components:
  parameters:
    XPaywallUser:
      name: X-Paywall-User
      in: header
      required: false
      schema:
        type: string
      description: >
        Optional user identifier provided by the developer.

        Can be used instead of the `user` property in the request body to
        associate the API call with a specific end user.
  securitySchemes:
    ApiKeyAuth:
      type: http
      scheme: bearer

````