Windsurf IDE API Configuration

Windsurf IDE: Custom API Configuration and Setup Guide

Windsurf is an AI-native integrated development environment that combines intelligent code editing with a powerful AI agent called Cascade. Originally built by Codeium, Windsurf provides an alternative to Cursor with its own unique approach to AI-assisted development. This guide covers how to set up Windsurf, configure custom API endpoints, and get the most out of its AI features.

Installation and Initial Setup

1. Download Windsurf from windsurf.com for your operating system (macOS, Windows, or Linux).
2. Run the installer and launch Windsurf.
3. Sign up or sign in with your Windsurf account.
4. When prompted, import your VS Code settings, extensions, and keybindings if migrating from VS Code or Cursor.

Windsurf is built on the VS Code codebase, so it supports VS Code extensions, themes, and keyboard shortcuts. Your existing workflow carries over seamlessly.

Understanding Windsurf's AI Features

Cascade — The AI Agent

Cascade is Windsurf's autonomous AI agent that can understand your codebase, make multi-file edits, run terminal commands, and iterate on its work. It is similar to Cursor's Composer Agent or Cline's agentic mode. Activate Cascade with Cmd+I (macOS) or Ctrl+I (Windows/Linux).

Autocomplete (Supercomplete)

Windsurf provides intelligent code completions as you type. Press Tab to accept suggestions. The autocomplete engine is context-aware and considers your open files, recent edits, and project structure.

Inline Editing

Select code and press Cmd+K to edit it with natural language instructions. This is useful for quick refactoring, adding error handling, or converting code patterns.

Chat Panel

Open the chat panel with Cmd+L for longer conversations about your code. Use @ to reference files and folders for precise context.

Configuring Custom API Endpoints

Windsurf supports custom model configurations, allowing you to use your own API keys and endpoints. Here is how to configure a custom API provider:

1. Open Windsurf Settings (Cmd+, or Ctrl+,).
2. Navigate to the Windsurf Settings section (not VS Code settings).
3. Look for the Model Configuration or AI Provider settings.
4. Configure your custom endpoint with the base URL, API key, and model name.

// Custom API configuration for relay service:
Provider: Custom / OpenAI Compatible
Base URL: https://claude4u.com/v1
API Key:  cr_your-relay-api-key
Model:    claude-sonnet-4-20250514

Windsurf Pricing Tiers

Understanding Windsurf's pricing helps you decide whether to use the built-in models or bring your own API key:

• Free tier: Limited Cascade credits and autocomplete. Good for trying Windsurf before committing.
• Pro ($15/month): More Cascade credits, priority access, and advanced features.
• Team ($30/user/month): Admin controls, centralized billing, and team management.

With a custom API key, you can extend or replace the built-in model access. This is particularly useful if you exhaust your Cascade credits or want to use specific models that are not available through Windsurf's built-in options.

Windsurf vs Cursor: Key Differences

Effective Usage Patterns

Using Cascade for Complex Tasks

// Open Cascade (Cmd+I) and describe your task:

"Implement user authentication with JWT tokens for this Express API.
Create the following:
1. User model with email, password hash, and created_at fields
2. Registration endpoint (POST /auth/register) with input validation
3. Login endpoint (POST /auth/login) that returns a JWT
4. Auth middleware that validates JWT tokens
5. Unit tests for all new functions"

Code Review with Chat

// Open chat (Cmd+L) and reference specific files:

@src/controllers/orderController.js
@src/services/orderService.js
Review these files for potential issues:
- Race conditions in order processing
- Missing error handling
- N+1 query problems
- Security vulnerabilities

Quick Edits with Inline Mode

// Select a function, press Cmd+K, and type:
"Add retry logic with exponential backoff for network failures"
"Convert this to use async iterators instead of callbacks"
"Add JSDoc comments with parameter and return type documentation"

Optimizing Performance

• Let indexing complete: Windsurf indexes your codebase for better AI responses. Let this process finish before asking complex questions.
• Use file references: The @ syntax for referencing files helps the AI focus on relevant context, improving both speed and accuracy.
• Choose the right tool: Use autocomplete for line-level completions, inline edit for function-level changes, and Cascade for multi-file tasks.
• Manage context wisely: Close irrelevant files before starting AI tasks. Open files are included in the AI's context window.

Troubleshooting

• Cascade not responding: Check your internet connection and API key configuration. Verify you have remaining Cascade credits if using the built-in models.
• Custom API errors: Verify the base URL format and API key. Test the endpoint with curl to confirm it is accessible.
• Slow autocomplete: Check if indexing is in progress. Large projects may take several minutes to index initially.
• Extensions not working: Windsurf supports most but not all VS Code extensions. Check the Windsurf documentation for known incompatibilities.

For developers who want a reliable AI coding experience with flexible model access, combining Windsurf with a relay service like claude4u.com provides the best of both worlds: Windsurf's polished IDE experience with the ability to use any model through a unified, reliable API endpoint.