OpenAI API vs Claude API: which should your app use?

In the OpenAI API vs Claude API decision, pick the Claude API if your app reads long documents, contracts or big knowledge bases, because Claude's current models price the full 1 million token context at the standard rate while OpenAI doubles input prices past 272,000 tokens. Pick the OpenAI API if you want voice, image generation and transcription from one vendor, or you already run on OpenAI and nothing is broken.

Quick answer: As of November 2026, the two APIs charge the same list price at three matched tiers: $10/$50, $2/$10 and $0.10/$0.50 per million input and output tokens. Both skip training on API data by default, both delete or expire logs within about 30 days, and both cut 50% for batch jobs. The real differences are long-prompt pricing, voice and image tools, and how each model handles your actual work.

OpenAI API vs Claude API: side-by-side

A token is a chunk of text, roughly three quarters of a word, and both companies bill per million tokens (MTok). Prices below are list prices as of November 2026, checked November 2, 2026, on the OpenAI API pricing page and Anthropic's Claude pricing page. Context windows come from each vendor's model pages.

OpenAI also sells GPT-6.1 Terra at $1 in and $5 out, and Anthropic sells Claude Opus 5.5 at $4 in and $20 out. Those two have no direct twin on the other side, so they're useful when you need something between the everyday and top tiers.

Which API is cheaper for a real business app?

At matched tiers, neither is cheaper on the price sheet. A worked example: a support chatbot handling 10,000 conversations a month, each sending 3,000 tokens in and getting 500 tokens back, uses 30 million input and 5 million output tokens. On GPT-6.1 Sol or Claude Sonnet 5.5 that's $60 plus $50, about $110 a month at list price, before any caching discount.

Three things move the real bill. First, long prompts: OpenAI's GPT-6.1 Sol model page says requests over 272,000 input tokens are billed at 2x input and 1.5x output for the whole request, while Claude Sonnet 5.5 and Opus 5.5 keep one rate across the full 1 million tokens. If your app feeds in whole case files or a year of emails, that gap is real money.

Second, caching. When your app sends the same instructions or documents again and again, both vendors bill repeats at a steep discount: $0.10 per million cached input tokens on both Sonnet 5.5 and GPT-6.1 Sol. Third, token counts differ. Anthropic says its newer tokenizer (the part that chops text into tokens) produces about 30% more tokens than its older one for the same text, so the only honest comparison is running your own prompts through both and reading the bills.

Identical price sheets don't mean identical bills: run your own prompts through both APIs and compare the invoices.

What happens to your data with each API?

Both vendors keep business data out of training by default. OpenAI's data controls guide says data sent to the API hasn't been used to train its models since March 1, 2023, unless you opt in. Anthropic's privacy center says it won't use API inputs or outputs to train its models by default, unless you send feedback or choose to share data.

Retention is close too. OpenAI keeps abuse monitoring logs, which can include prompts and responses, for up to 30 days. Anthropic says it deletes API inputs and outputs within 30 days, with exceptions for features like its Files API, legal holds and flagged policy violations. Both offer zero data retention, but only by separate approval or agreement, so ask for it early if you handle health, legal or financial records.

Both also charge a 10% premium to keep processing in a specific region: OpenAI for regional processing on models released since March 5, 2026, and Anthropic for US-only inference on Claude 4.6 and later. If a client contract says data must stay in the US, budget that 10% from day one.

When should you choose the OpenAI API?

OpenAI is the better fit when your product does more than read and write text. Its price list covers voice sessions, live transcription, translation and image generation in one account, so a restaurant ordering assistant that answers the phone, or a real estate app that generates listing images, can run on one vendor and one bill.

• You need voice or phone features (OpenAI's gpt-live-1 voice sessions are listed at $0.05 a minute).
• You want image generation or audio transcription next to your chat features.
• Your team or your existing tools already run on OpenAI, and switching would mean rework with no clear gain.
• You want built-in hosted tools like web search ($10 per 1,000 calls) and file search on the same platform.

One caution: OpenAI is winding down its fine-tuning platform (training a custom version of a model on your examples), and it's closed to new users. If a vendor pitches you a fine-tuned model as the plan, ask what happens when that base model retires.

When should you choose the Claude API?

Claude is the better fit when the job is reading, writing and reasoning over a lot of text. Every current Claude model has a 1 million token window, according to Anthropic's models overview, and the main models charge the same rate whether you send 9,000 tokens or 900,000. That suits contract review, insurance claim summaries, policy lookups and research assistants.

• Your app reads long documents, manuals or full customer histories in one request.
• You're building an AI agent, software that takes steps on its own like updating a CRM or drafting replies, and you want a long-running model like Opus 5.5.
• You want a mid-priced tier: Opus 5.5 sits at $4 in and $20 out, between the everyday and top tiers.
• You plan to run large overnight jobs, where the 50% batch discount and cheap cache reads stack.

Many good apps use both. A router, a small piece of code that picks a model per request, can send quick classification to the cheapest tier and hard questions to a bigger model. Building that way also means you're never locked in if one vendor changes prices.

How do you decide in a week, not a quarter?

You don't need a long evaluation. Run this checklist with 50 to 100 real examples from your business, such as past support tickets or old quotes, with personal details removed.

1. Write down the one job the AI must do well, and what a wrong answer costs you.
2. Measure your typical prompt size. If it's regularly over 272,000 tokens, price long-context requests on both.
3. Run the same examples through the matched tier on each API and score the answers blind.
4. Compare the actual bills from those runs, since token counts differ between vendors.
5. Check data terms: training defaults, retention, and whether you need zero data retention or US-only processing.
6. List the extras you need now or within a year: voice, images, transcription, web search.
7. Pick the winner, but build behind a router so you can switch later.

If you'd rather have a team run that test and build the app around the winner, that's the work our AI agent development team does. Our guide to building an AI agent walks through the rest of the project.

What does it cost to build an app on either API?

The API bill is usually the small number. The bigger cost is the software around it: connecting your CRM or booking system, handling errors, logging answers, and giving staff a way to review them. Eltherion's pricing calculator puts an AI system MVP with two integrations at $24,000 to $80,000, a v1 product at $30,000 to $101,000, and a full platform at $40,000 to $136,000.

These are estimate ranges; the fixed price comes after a free scoping call. Eltherion projects start as low as $1,000 for small, tightly scoped work, like wiring one AI step into a tool you already use. You can try your own inputs in the cost calculator.

Frequently asked questions

Is Claude better than ChatGPT for business?

ChatGPT is OpenAI's app, and Claude is Anthropic's; the APIs are what you build your own software on. Neither wins every task. Claude's current models handle very long documents at one price, while OpenAI offers more voice and image tools in one place. Test both on 50 real examples from your business before you commit.

Can I switch from the OpenAI API to the Claude API later?

Yes, if the app was built for it. The request formats differ, so code written directly against one API needs changes to use the other. Teams that put a thin layer between the app and the model can usually switch in days. Prompts may still need tuning, because each model responds a little differently to the same instructions.

Does OpenAI or Anthropic train on my API data?

Not by default. OpenAI says API data hasn't been used for training since March 1, 2023, unless you opt in. Anthropic says it won't use API inputs or outputs for training by default, though feedback you explicitly submit can be used. Both keep some logs for up to about 30 days for safety reviews.

Which API is cheaper for a small business chatbot?

At list price they're tied. Claude Haiku 5.5 and GPT-6 Luna both charge $0.10 per million input tokens and $0.50 per million output tokens as of November 2026, and the everyday tiers both charge $2 and $10. Your bill depends on prompt length, caching and how many tokens each model counts for your text.

What to do next

Pull 50 real examples from your business this week and run them through the matched tier on both APIs. You'll have a clear answer on quality and cost in a few days, not months.

If you want help picking the model and building the app around it, get a free project estimate. We'll scope it, give you a fixed price, and tell you honestly if an off-the-shelf tool already does the job.