Skip to main content

​
Overview

The Apply API enables lightning-fast code editing at 10,500+ tokens/second with 98% accuracy. This OpenAI-compatible endpoint intelligently merges code changes while preserving structure and formatting.

​
Models

Choose the model that best fits your use case:

​
Message Format

The Apply API uses a structured XML format within the message content: 
<instruction>Brief description of what you're changing</instruction>
<code>Original code content</code>
<update>Code snippet showing only the changes with // ... existing code ... markers</update>

​
Format Guidelines

  • <instruction>: Optional but recommended. Use first-person, clear descriptions
  • <code>: The complete original code that needs modification
  • <update>: Show only what changes, using // ... existing code ... for unchanged sections

​
Usage Examples

import OpenAI from "openai";

const openai = new OpenAI({
  apiKey: "YOUR_API_KEY",
  baseURL: "https://api.morphllm.com/v1",
});

const instruction = "I will add error handling to prevent division by zero";
const originalCode = "function divide(a, b) {\n  return a / b;\n}";
const codeEdit = "function divide(a, b) {\n  if (b === 0) {\n    throw new Error('Cannot divide by zero');\n  }\n  return a / b;\n}";

const response = await openai.chat.completions.create({
  model: "morph-v3-fast",
  messages: [
    {
      role: "user",
      content: `<instruction>${instruction}</instruction>\n<code>${originalCode}</code>\n<update>${codeEdit}</update>`,
    },
  ],
});

const mergedCode = response.choices[0].message.content;

​
Error Codes

edit_file Tool Guide

Build AI agent tools with Morph Apply

More Examples

See more implementation patterns