Should your coding agent use your ChatGPT or Claude plan, or a separate API?
If you already pay for ChatGPT Plus or Pro or Claude Pro or Max and your agent supports plan login, use the plan until you keep running into its five-hour or weekly limits. A separate API makes sense for agents that run unattended, work that needs several vendors' models, team budgets, agents without plan login, and a monthly cost you can plan.
Which agents accept plan login today
| Agent | ChatGPT plan | Claude plan | Own API key | Custom base URL |
|---|---|---|---|---|
| Claude Code | No | Yes | Yes | Yes, ANTHROPIC_BASE_URL |
| Codex CLI | Yes | No | Yes | Yes, model_providers |
| Amp | Yes, since Sep 10 | Pro or Max, since Oct 10 | Yes | Yes |
| Devin Desktop | Go, Plus or Pro, since Sep 29 | Not documented | Not in current docs | Not documented |
| Kilo Code | Plus or Pro, since Sep 29 | Not documented | Yes | Yes |
| Warp | Yes, since Sep 23 | No | Yes | Yes |
| Cline | Yes | Through the Claude CLI | Yes | Yes |
| Roo Code | Plus or Pro | Not documented | Yes | Yes |
| OpenCode | Plus or Pro | No, removed in 1.3.0 | Yes | Yes |
| Cursor | Not documented | Not documented | Yes | Not documented |
| GitHub Copilot | No | No | Yes, preview for orgs | Yes, in VS Code |
All dates 2026. Devin Desktop was called Windsurf. "Not documented" means the vendor's docs don't mention it. Sources: Claude Code, Codex, Amp, Devin, Kilo, Warp, Cline, Roo Code, OpenCode, Cursor, Copilot.
What plan login gives you
Plan login lets the agent spend your subscription's allowance instead of a metered key: ChatGPT Plus or Claude Pro at $20 a month, ChatGPT Pro at $100, $200 or $500, Claude Max at $100 or $200. For daily coding that fits the limits, no API route comes close on price.
- On Claude plans, chat and coding share one allowance: Anthropic counts all activity in Claude and Claude Code against the same limits. On ChatGPT plans, Codex shares its allowance with ChatGPT Work; OpenAI lists regular chat separately.
- Plus, Claude Pro and Max have a five-hour window and a weekly limit, and you need room in both. ChatGPT Pro has no five-hour limit, though OpenAI says weekly limits may apply. Plan by plan in Codex usage limits and Claude Code pricing.
- Neither vendor publishes the allowance in tokens: OpenAI gives message ranges and Anthropic gives multiples of Pro. Recent changes are logged in AI coding plan changes.
- At the limit, what happens depends on the agent. Kilo stops with no fallback, Devin switches to your Devin quota, and Claude Code and Codex let you buy extra usage at API rates.
- A plan only covers its own vendor's models. In Devin, only GPT usage bills to your ChatGPT plan.
When a separate API wins
- Your agent runs unattended or around the clock. Scheduled jobs, background agents and CI runs don't wait for a window to reset, and they eat the allowance you need when you sit down to code.
- You want models from more than one vendor. One key can call Claude, GPT and open models, and the agent can switch per task.
- A team shares the bill. Plus, Pro and Max are personal accounts, so a team needs keys per person or per app with one budget it can see.
- Your agent has no plan login. Cursor and GitHub Copilot take your own API key but not a ChatGPT or Claude plan; Cursor's own plans are covered in Cursor pricing.
- You need to plan the cost. A ChatGPT or Claude plan has a fixed price but an unpublished allowance, and a metered API has a published rate but no fixed total. A budgeted API plan has a fixed price and a stated budget.
A month of agent work next to the plan prices
We priced every coding-agent request on the Standard Compute gateway from September 13 to October 12, 2026 at list prices. The median active day had 94 requests and 8.5M tokens and cost $3.53 on Sonnet 5.5; a busy day, the 90th percentile, had 491 requests and cost $28.97. On GPT-6 Luna, an efficient model, the median day cost $0.23. At these rates, $20 pays for 5.7 median Sonnet days and $100 for 3.5 busy ones.
Which one fits you
- You already pay, your agent supports plan login and you rarely hit a limit: use the plan.
- You hit the five-hour window most days: switch routine work to a lighter model first, then decide between a bigger plan and an API for the overflow.
- You code a few days a month: a metered API key costs less than any plan.
- Your agent also runs while you are away: give that work its own key and keep the plan for your own sessions.
The catch
Nobody outside OpenAI and Anthropic can tell you how much agent work a plan buys, and both can change it without changing the price: on September 29 OpenAI cut the allowance for new Pro 200 subscribers at the same price. On the API you know the token price but not the total, and one busy day can cost more than a month of Plus. Our day costs come from other coding agents priced at list rates, so check your own usage page after a week before you switch.
Where Standard Compute fits
Standard Compute is a separate API plan from $19 a month with a fixed monthly compute budget and no five-hour or weekly windows. Requests stop when the budget is used, with no overage charges. Claude Code connects through /v1/messages, Codex through /v1/responses, and OpenCode lists it in models.dev. It does not include a ChatGPT or Claude plan, and the $19 plan's $20 budget is sized for moderate use; smart routing sends routine steps to efficient models so it lasts longer.
FAQ
Can I use my ChatGPT Plus subscription in coding agents other than Codex?
Yes. Amp, Devin Desktop (formerly Windsurf), Kilo Code, Warp, Cline, Roo Code and OpenCode accept ChatGPT login, and Devin also takes Go. Only OpenAI's models bill to the plan; other models in those agents still need their own key or credits.
Can I use my Claude Pro or Max subscription outside Claude Code?
In a few places. Amp added Claude Pro and Max login on October 10, 2026, running those threads through the Claude Agent SDK, and Cline can use the plan through the Claude CLI. OpenCode removed its Claude plan plugins in version 1.3.0, and Warp says it can't connect a Claude subscription.
Can I spend the Claude Max API credits in Claude Code?
Not in interactive Claude Code. Anthropic's monthly credits ($100 on Max 5x, $200 on Max 20x, $20 or $100 per Team seat, pooled up to $500) cover the Claude API, Managed Agents and the Agent SDK, but not Claude Code in the terminal, IDE, desktop or web. They suit a script or background agent you would otherwise pay API rates for.
Does my coding agent use up my ChatGPT or Claude chat messages?
On Claude, yes: Anthropic says all activity in Claude and Claude Code counts against the same limits. On ChatGPT, Codex shares its allowance with ChatGPT Work, and OpenAI lists regular chat as separate.
Is a ChatGPT or Claude plan cheaper than the API for coding?
For daily coding that fits the limits, yes, by a wide margin: a $20 plan costs about as much as six median days on Sonnet 5.5 at list prices. For a few days a month, the API costs less.
What happens when my plan runs out in the middle of a task?
Codex finishes the turn already running, then stops until the reset unless you buy credits. Claude Code pauses and shows when the window reopens. In other agents it varies: Kilo stops with no fallback to an API key, and Devin switches to your Devin quota.