How to Switch from ChatGPT to Claude Code Without Losing Your Context

Why Developers Are Switching

Claude Code has become the most-used AI coding assistant in 2026, with 46% of developers preferring it over alternatives. The reasons are clear: it runs in your terminal, understands your entire codebase, and its agentic capabilities let it make multi-file changes autonomously.

But if you've been using ChatGPT for months, you've built up a library of custom instructions, coding preferences, and project context. Manually rewriting all of that for Claude's format is tedious and error-prone.

The Problem: Different Formats

ChatGPT and Claude store instructions in completely different ways:

• ChatGPT uses custom instructions and memory stored server-side, plus CHATGPT.md project files
• Claude Code uses CLAUDE.md files (project-level) and ~/.claude/ (global settings)

It's not just the file format that differs — the conventions are different too. ChatGPT instructions tend to be conversational, while Claude Code's CLAUDE.md follows a specific markdown structure with rules, preferences, and project context.

Copy-pasting doesn't work. You need a translation layer.

The Solution: One Command

memoir can translate your ChatGPT instructions into Claude Code format automatically using AI:

memoir migrate --from chatgpt --to claude

This doesn't just copy your text. It actually rewrites your instructions to follow Claude Code's conventions:

• Converts conversational instructions into structured CLAUDE.md format
• Maps ChatGPT "custom instructions" to Claude's project rules
• Preserves your coding style preferences, language choices, and patterns
• Handles format differences (ChatGPT's free-form vs Claude's markdown structure)

Step-by-Step Migration

1. Install memoir

npm install -g memoir-cli

2. Export your ChatGPT instructions

Create a file called CHATGPT.md in your project root with your custom instructions. You can export these from ChatGPT's settings under "Customization" → "Custom Instructions."

# My ChatGPT Custom Instructions

## How would you like ChatGPT to respond?
- Always use TypeScript, never plain JavaScript
- Prefer functional components with hooks
- Use Tailwind CSS for styling
- Write concise code with minimal comments
- When debugging, check the simplest explanation first

## What would you like ChatGPT to know about you?
- I'm a full-stack developer working with Next.js
- My projects use Supabase for the backend
- I prefer bun over npm
- I deploy to Vercel

3. Run the migration

memoir migrate --from chatgpt --to claude

memoir reads your CHATGPT.md and generates a properly formatted CLAUDE.md with your preferences translated to Claude's conventions.

4. Preview before applying

memoir migrate --from chatgpt --to claude --dry-run

Use --dry-run to preview the generated CLAUDE.md without writing it to disk.

Migrate to Any Tool, Not Just Claude

memoir supports migration between any combination of 11 tools:

# ChatGPT → Cursor
memoir migrate --from chatgpt --to cursor

# Claude → Gemini
memoir migrate --from claude --to gemini

# Cursor → Claude
memoir migrate --from cursor --to claude

# One tool → all tools
memoir migrate --from chatgpt --to all

Each migration uses AI to translate between the specific conventions of each tool, not just copy-paste.

Keep Both Tools in Sync

Many developers use ChatGPT and Claude together. memoir lets you maintain configs for both and keep them synchronized:

# Back up everything
memoir push

# Restore on a new machine (both tools get their configs)
memoir restore

70% of developers use 2-4 AI tools. memoir is built for this reality.

FAQ

Do I need an API key for migration?

The AI-powered translation uses a Gemini API key for the rewriting step. memoir will prompt you if one isn't configured. Basic file-format conversion works without any API key.

Will this overwrite my existing CLAUDE.md?

memoir will ask for confirmation before overwriting. Use --dry-run to preview first.

Can I migrate conversation history?

memoir migrates instructions and preferences, not conversation history. Your coding style, rules, and preferences transfer — individual conversations do not.