Most teams do not need to rewrite their application to leave per-token OpenAI billing. unlimitedcodex uses the same OpenAI-compatible request shapes - you change the base URL, replace the API key after manual setup delivery, and map model IDs to the ChatGPT 5.5 Ultra and Codex values in your setup email.
Operator-reviewed
Maintained by the unlimitedcodex operator team responsible for manual API setup delivery, base URL handoff, package dates, and customer support workflows.
What transfers unchanged
Chat completion payloads, embeddings requests, image request shapes, Bearer authentication, and most SDK configuration patterns stay the same.
If you already use environment variables for secrets, keep that pattern. Store the delivered unlimitedcodex key server-side and point clients at the delivered /v1 base URL.
Migration checklist
Choose Unlimited Weekly for a short sprint or Unlimited Monthly for ongoing builds. Complete Stripe checkout and wait for manual setup delivery.
Replace OPENAI_API_KEY with your delivered unlimitedcodex key and update the base URL in your OpenAI-compatible client.
Map model names to gpt-5.5 or Codex IDs from your setup email, then run a low-volume smoke test before production traffic.
When OpenAI API is still the better fit
Stay on first-party OpenAI when you need official enterprise contracts, same-day first-party feature access, or procurement through OpenAI directly.
Choose unlimitedcodex when predictable weekly or monthly spend matters more than first-party billing for heavy ChatGPT 5.5 Ultra and Codex workloads.