Agent comparison – Claude vs. ChatGPT vs. Copilot
In 2026, "AI coding agent" is an umbrella term for very different tools. Some live in the terminal, some in the editor, some in messengers. Some are tightly coupled to a model provider, others are agnostic and can run Claude, GPT-5 or a local model at will. This guide gives you a clear map: which agent comes from which camp, what it can do, when to pick it – and when not to.
1. Quick decision guide
| You want… | Pick |
|---|---|
| Pair programming in the terminal, best reasoning quality | Claude Code |
| Pair programming in the editor, native VS Code integration | GitHub Copilot (Chat + Agent Mode) |
| OpenAI models in the terminal | Codex CLI |
| Fast headless loop without UI, fire-and-forget | Open Ralph Wiggum |
| A swarm and orchestration layer on top of Claude Code or Codex | Ruflo |
| One MCP endpoint over many SaaS tools | Slim Tools |
| Personal all-purpose agent with memory, voice, messengers | Hermes Agent |
| Self-hosted messaging gateway, Claude in WhatsApp/Telegram | OpenClaw |
| Editor agent with multi-file refactor | Cursor Agent |
| Open-source agent, model-agnostic, local models | OpenCode |
| Tasks in the cloud, branches/PRs without local setup | OpenAI Codex Cloud / Copilot Coding Agent / Claude on Web |
2. The three camps
┌─────────────────────────┬─────────────────────────┬─────────────────────────┐
│ ANTHROPIC │ OPENAI │ GITHUB │
│ (Claude) │ (ChatGPT) │ (Copilot) │
├─────────────────────────┼─────────────────────────┼─────────────────────────┤
│ Claude Code (CLI/IDE) │ Codex CLI │ Copilot (VS Code) │
│ Claude API + Agent SDK │ OpenAI Agents SDK │ Copilot CLI │
│ Claude Skills │ Custom GPTs │ Copilot Coding Agent │
│ Claude on the Web │ Codex Cloud │ Copilot Workspace │
│ MCP (inventor) │ Function Calling │ Copilot Extensions │
└─────────────────────────┴─────────────────────────┴─────────────────────────┘
Third-party & Open Source – model-agnostic:
Cursor Agent · OpenCode · [Ruflo](./ruflo) · Hermes · OpenClaw · Open Ralph Wiggum · [Aider](./aider.mdx) · Continue
3. Anthropic / Claude – the agents
Claude Code
What it is: Anthropic's official coding CLI, running in the terminal and in IDE plugins (VS Code, JetBrains).
| Model | Claude Opus 4.7 (1M ctx), Sonnet 4.6, Haiku 4.5 |
| Interface | Terminal, VS Code extension, JetBrains plugin, Web (claude.ai/code) |
| Tools | Read/Write/Edit, Bash, WebFetch, MCP client, subagents, Skills |
| Strengths | Reasoning on large codebases, clean diff style, prompt caching, Skill system |
| Weaknesses | Tightly coupled to Anthropic; more expensive per token than GPT tier 2 |
| Ideal use case | Complex refactors, architecture migrations, anything with large context |
npm install -g @anthropic-ai/claude-code
claude # interactive
Claude Agent SDK
What it is: A programmatic SDK to build your own agents on top of Claude – including tool calling, memory and subagent spawning.
- Languages: Python, TypeScript
- Distributes MCP tools, Skills, hooks and subagents
- When to pick? When you ship your own agents into production rather than just using Claude Code.
Claude Skills
Reusable Markdown modules with YAML frontmatter that act as procedural memory. They work in Claude Code and in the Agent SDK.
MCP – Model Context Protocol
An open standard invented by Anthropic that lets agents speak to arbitrary tool servers (filesystem, GitHub, DBs, your own servers). Now also supported by OpenAI and others – MCP became the de-facto standard in 2025/2026.
4. OpenAI / ChatGPT – the agents
Codex CLI
What it is: OpenAI's official coding CLI – the GPT-camp counterpart to Claude Code.
| Model | GPT-5, GPT-5-Codex, o-series (reasoning) |
| Interface | Terminal, VS Code extension |
| Tools | File edit, shell, web, MCP client |
| Strengths | Fast, cheap on the mini tier, good test-first workflows |
| Weaknesses | Shorter default context than Claude Opus, less mature Skill system |
| Ideal use case | Fast iterations, test-driven development, cost-sensitive |
npm install -g @openai/codex
codex
OpenAI Agents SDK
A Python/TypeScript SDK for agentic apps on top of OpenAI. Function-calling centric, good streaming story, integrates with the Assistants API and MCP.
When to pick? When you stay in the OpenAI ecosystem (embeddings, vector stores, RAG pipelines) and build your own agent.
Custom GPTs
Configurable GPT instances in the ChatGPT UI with Actions (HTTP APIs) and knowledge files. Not a coding agent in the strict sense, but relevant for domain assistants and internal tools.
Codex Cloud
OpenAI's cloud coding service: you give it a task + repo URL, Codex Cloud opens a PR. The counterpart to Copilot Coding Agent and Claude on the Web.
5. GitHub / Copilot – the agents
GitHub Copilot (Editor)
What it is: The classic – inline code completion + chat in VS Code, JetBrains, Visual Studio, Vim/Neovim, Xcode.
| Model | Selectable: GPT-5, Claude Sonnet 4.6, Gemini, o-series |
| Interface | Editor inline + chat panel + Agent Mode |
| Tools | Workspace index, tests, terminal (Agent Mode) |
| Strengths | Deepest IDE integration, native GitHub/PR context, multi-model selection |
| Weaknesses | Editor-centric, less good for pure CLI workflows |
| Ideal use case | Daily coding in the editor, staying "in flow" |
Copilot Agent Mode
Inside VS Code: Copilot takes over multi-file edits, runs tests, corrects itself – similar to Cursor Agent. Free model choice (including Claude!).
Copilot CLI
GitHub's official terminal agent, optimized for repo context and Git/PR operations.
gh extension install github/gh-copilot
gh copilot suggest "find files modified in last commit"
Copilot Coding Agent
Asynchronous cloud agent: you assign an issue, it creates a PR on its own branch, runs CI and reacts to review comments. Counterpart to Codex Cloud / Claude on the Web.
Copilot Extensions
Extensibility: third parties (Sentry, Docker, Stripe etc.) build their own Copilot skills. Similar to Custom GPTs, but in a dev context.
6. Model-agnostic agents (third-party & Open Source)
These tools are not tied to a model provider – you choose which LLM runs underneath.
Cursor Agent
| What | Editor-first agent (Cursor IDE) with a headless CLI (cursor-agent) |
| Models | Anthropic, OpenAI, own |
| Strength | Multi-file refactor, Composer mode, very fast apply loops |
| Use case | Editor-heavy users who want more than Copilot |
OpenCode
| What | Open-source coding CLI, actively developed |
| Models | any (Anthropic, OpenAI, OpenRouter, Ollama, local models) |
| Strength | Plugin system, MCP, free license, runs locally |
| Use case | Privacy/self-hosting, cost-conscious teams |
Slim Tools
| What | Hosted MCP and OpenAPI orchestration runtime |
| Models | Model-agnostic through the client layer |
| Strength | One MCP endpoint, capability discovery, cross-service fan-out |
| Use case | Tool-heavy agents spanning multiple SaaS systems |
Ruflo
| What | Multi-agent orchestration harness on top of Claude Code and Codex |
| Models | Multi-provider through the underlying agent stack |
| Strength | Swarms, memory, hooks, plugins, MCP server, federation |
| Use case | Teams or power users who want workflow orchestration, not just a single coding agent |
Aider
CLI pair-programmer that works Git-centric (every change = commit). Model-agnostic, older and very stable.
Continue
Open-source coding agent available as a CLI, VS Code extension, and JetBrains plugin. Now in a final-release, read-only state after the Cursor acquisition, but still useful as a configurable reference workflow.
Hermes Agent
General-purpose agent with memory, skills self-authoring, voice and 18+ messaging channels. Self-improving: writes its own skills from experience. Model-agnostic.
OpenClaw
Self-hosted messaging gateway: brings your coding agent into WhatsApp, Telegram, Slack & co. Multi-agent, sandboxing, AgentSkills-compatible.
Open Ralph Wiggum
Autonomous loop runner: calls Claude Code, Codex, Copilot CLI, Cursor or OpenCode in an endless loop until the acceptance criterion is met. Agent rotation for model comparison.
SantanderAI
Not a single agent, but a public open-source organization around Ralph, repo-memory skills, guardrails, and vendor-neutral LLM tooling. Best viewed as a toolbox for building your own agent stack.
7. Large comparison table
| Tool | Camp | UI | Models | Self-host | Best for |
|---|---|---|---|---|---|
| Claude Code | Anthropic | CLI / IDE / Web | Claude only | – | Reasoning-heavy coding |
| Claude Agent SDK | Anthropic | Library | Claude only | – | Building your own agents |
| Codex CLI | OpenAI | CLI / IDE | GPT only | – | Fast TDD loops |
| OpenAI Agents SDK | OpenAI | Library | GPT only | – | Custom agents in the OpenAI stack |
| Codex Cloud | OpenAI | Web / GitHub | GPT only | – | Async cloud coding |
| Copilot (Editor) | GitHub | IDE | Multi (GPT/Claude/Gemini) | – | Daily editor coding |
| Copilot Agent Mode | GitHub | IDE | Multi | – | Multi-file tasks in the editor |
| Copilot CLI | GitHub | CLI | Multi | – | Git/repo operations |
| Copilot Coding Agent | GitHub | GitHub.com | Multi | – | Async PR bot |
| Cursor Agent | Third-party | IDE / CLI | Multi | – | Editor-heavy refactors |
| OpenCode | OSS | CLI | any | ✅ | Privacy / local |
| Slim Tools | Third-party | MCP runtime | Client-agnostic | – | Tool orchestration across SaaS |
| Ruflo | OSS | CLI / MCP / plugins | Multi | ✅ | Agent orchestration layer |
| Aider | OSS | CLI | any | ✅ | Git-first pair coding |
| Continue | OSS | IDE | any | ✅ | Copilot alternative |
| Hermes | OSS | TUI / messenger | any | ✅ | Personal all-purpose agent |
| OpenClaw | OSS | Messenger / Web | any | ✅ | Messaging gateway |
| Open Ralph Wiggum | OSS | CLI | any (5 agents) | ✅ | Autonomous loops |
8. Feature matrix
| Feature | Claude Code | Codex CLI | Copilot | Cursor | OpenCode | Hermes | OpenClaw | Ralph |
|---|---|---|---|---|---|---|---|---|
| Inline edit in editor | ⚪ | ⚪ | ✅ | ✅ | ⚪ | ⚪ | ⚪ | ⚪ |
| Terminal mode | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ | ⚪ | ✅ |
| Multi-file refactor | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ |
| Subagents | ✅ | ⚪ | ⚪ | ⚪ | ⚪ | ✅ | ✅ | ⚪ |
| MCP client | ✅ | ✅ | ⚪ | ⚪ | ✅ | ✅ | ✅ | ⚪ |
| Skills / procedural memory | ✅ | ⚪ | ⚪ | ⚪ | ⚪ | ✅ | ✅ | ⚪ |
| Cross-session memory | ✅ | ⚪ | ⚪ | ⚪ | ⚪ | ✅ | ✅ | ⚪ |
| Voice mode | ⚪ | ⚪ | ⚪ | ⚪ | ⚪ | ✅ | ⚪ | ⚪ |
| Messenger integration | ⚪ | ⚪ | ⚪ | ⚪ | ⚪ | ✅ | ✅ | ⚪ |
| Cloud async mode | ✅ | ✅ | ✅ | ⚪ | ⚪ | ⚪ | ⚪ | ⚪ |
| Sandboxing | partial | partial | ⚪ | ⚪ | partial | ✅ | ✅ | ⚪ |
| Model choice | ⚪ | ⚪ | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ |
| Agent rotation | ⚪ | ⚪ | ⚪ | ⚪ | ⚪ | ⚪ | ⚪ | ✅ |
| Self-hosting | ⚪ | ⚪ | ⚪ | ⚪ | ✅ | ✅ | ✅ | ✅ |
| Self-improvement (Skills) | ⚪ | ⚪ | ⚪ | ⚪ | ⚪ | ✅ | ⚪ | ⚪ |
9. Use-case recommendations
"I'm a solo dev and want to just get started."
→ Copilot in the editor (familiar) or Claude Code in the terminal (more power). Both can run in parallel.
"I work on a large, complex codebase."
→ Claude Code with Opus 4.7 (1M context) – nothing else plays in this league. Pair with Cursor Agent for actual multi-file apply loops in the editor.
"I hate manual clicking, loops must run autonomously."
→ Open Ralph Wiggum – write acceptance criteria as tests, let Ralph run, go to lunch.
"I want multiple agent roles, memory, and automation around my coding agent."
→ Ruflo – especially when Claude Code or Codex alone feels too isolated and you want an orchestration layer.
"Privacy is mandatory, everything local."
→ OpenCode + Ollama/vLLM. No code leaves the machine. Optionally Hermes as a wrapper for memory/skills.
"I want a personal agent that comes with me everywhere."
→ Hermes with a Telegram/Discord gateway, optionally voice mode.
"I want coding agents in the team chat (WhatsApp/Slack)."
→ OpenClaw – self-hosted gateway, multi-agent, pairing allowlists.
"Async cloud workflows, the bot should open PRs."
→ Copilot Coding Agent (GitHub-native) or Codex Cloud (OpenAI-native) or Claude on the Web (Anthropic-native).
"I want to compare models directly."
→ Open Ralph Wiggum with --rotation, or Copilot Agent Mode with a model switcher, or Cursor with per-request model choice.
10. Cost – rough orientation
2026-05. Always verify on the vendor's pages.
| Tier | Tools | Idea |
|---|---|---|
| Pro subscription (~$20/month) | ChatGPT Plus, Claude Pro, Copilot Individual | Editor plugins + Web UI, "all you can eat" with throttling |
| Pro Max / Team (~$100–200/month) | Claude Max, ChatGPT Pro, Copilot Business | Higher quotas, team features |
| API per token | Claude API, OpenAI API, OpenRouter | Pay-as-you-go, ideal for always-on agents |
| Self-hosted local | Ollama, vLLM + OpenCode/Aider | Hardware cost, but no token price |
Rule of thumb: For active editor use, a subscription is worth it. For background loops/agents (Ralph, Hermes), API-per-token quickly costs more than a Pro subscription, but it's more transparent.
11. Security checklist (cross-cutting)
- Never put API keys in prompts or committed configs →
.env+.gitignore - Clone sensitive repos in a VM/container before enabling auto-approve
- Control auto-commits – check
git log --onelineregularly - MCP servers are untrusted code – they see files and tool outputs
- Read third-party Skills/plugins before enabling them
- Protect messaging gateways with pairing allowlists (OpenClaw, Hermes)
- Cloud agents (Copilot Coding Agent, Codex Cloud) have repo write access – take PR reviews seriously
- Prompt injection is real: incoming data (tickets, mails, issues) can hijack the agent
12. How to combine them (example stack)
A workable setup for a 1-person dev:
┌─────────────────────────────────────────────────────────────────┐
│ Editor (VS Code) │
│ └─ GitHub Copilot for inline completion │
│ └─ Claude Code Extension for reasoning-heavy tasks │
├─────────────────────────────────────────────────────────────────┤
│ Terminal │
│ └─ Claude Code CLI for architecture, large diffs │
│ └─ Codex CLI for quick mini-tasks │
│ └─ Open Ralph Wiggum for autonomous PRD execution │
├─────────────────────────────────────────────────────────────────┤
│ Personal layer │
│ └─ Hermes (Telegram bot) Memory, reminders, voice │
├─────────────────────────────────────────────────────────────────┤
│ Cloud (async) │
│ └─ Copilot Coding Agent for issue-to-PR tasks │
└─────────────────────────────────────────────────────────────────┘
→ If you run Hermes and OpenClaw in parallel, read the guide Running OpenClaw + Hermes in parallel first – otherwise the bots will steal each other's Telegram updates.
13. Further reading
Anthropic / Claude
OpenAI / ChatGPT
GitHub / Copilot
Third-party / OSS
"Pick the smallest agent that fits your loop. Stack only when each layer earns its keep."