Changing the model name takes a minute. Knowing your JSON, tool calls and answers still hold up takes testing. We replay your real prompts on the replacement and show you exactly what changed.
Until the date OpenAI lists on its deprecations page (counted to 00:00 UTC; OpenAI doesn't give a time of day).
Three steps. You stay in control of your code and your key.
Paste code or a public GitHub repo. The checker runs in your browser and lists every retiring model ID, its shutdown date and the vendor's suggested replacement.
Send 30–200 real prompt/response pairs. We run them on the replacement model with a key you create for the job, then compare JSON validity, tool calls, refusals, length and cost.
Read the report and fix it yourself, or have us update model IDs, prompts and schemas, re-run the replay, and hand you a pull request to review.
One-time prices. Order by email; we invoice before work starts. Model usage during replays bills to your own API account, with no markup.
See what's affected.
See what breaks before your users do.
We do the migration, you review it.
Taken from the vendors' own pages, last checked 2026-11-04.
claude-sonnet-4-5-20250929 retires → claude-sonnet-5-5
gpt-5, gpt-5-mini, gpt-5-nano, gpt-5-pro, o3, o3-pro → gpt-5.6-sol / -terra / -luna
No new fine-tuning jobs for existing customers. tts-1, tts-1-hd shut down.
GPT-4o, GPT-4o mini, GPT-4.1, GPT-4.1 mini, and fine-tunes built on them → gpt-6-luna
whisper-1, gpt-4o-transcribe and related transcription models
Sources: OpenAI deprecations · Anthropic model deprecations
Straight answers.
Often, yes, and the free checker shows you where. The risk is behavior: a new model may format JSON differently, pick different tool arguments, or refuse things the old one answered. The replay is how you find out on your own traffic.
No. Pasted code is scanned in your browser. For repo URLs, your browser reads public files straight from GitHub.
A JSONL file of prompt/response pairs, or a log export we can convert, plus an API key you create just for this job with a spending limit. Revoke the key when we're done.
Please remove it before sending. We'll send a redaction checklist. We delete your samples 30 days after delivery.
No. A replay shows how the new model handles the prompts you sent. It can't cover every possible input. If we find nothing worth fixing, the report says so.
No. Northgate Labs is independent.