AionUI
Set up Half Off Dev in AionUI as an OpenAI-compatible provider, in one click or by hand, and chat with Claude, GPT and Gemini at half price.
AionUI is an open-source desktop app that puts a graphical interface on top of AI models. It accepts Half Off Dev as an OpenAI-compatible provider, so a single key brings Claude, GPT and Gemini into it at half their official prices. Create an API key first.
Import in one click#
From API keys, open Use in tools → AionUI and click Open in AionUI. AionUI must be installed; it receives the provider with your key. A brand-new key is filled in already. For an older one, paste the whole key into the dialog, since Half Off Dev can't show a stored key again.
Manual setup#
Add a provider in AionUI using:
| Field | Value |
|---|---|
| Provider type | OpenAI-compatible (or "New API") |
| API host | https://halfoff.dev |
| API key | your ho-... key |
AionUI adds /v1 to the host by itself. Once the provider is saved, add model ids, for instance gemini-3.1-pro, claude-sonnet-5.5 or gpt-6.1-sol. The model list shows all of them.
Fixing errors#
| What you see | What to do |
|---|---|
401 Invalid or revoked API key | The key was mistyped, cut short or revoked. Paste it again or make a new one. |
404 Model '...' is not available | That id doesn't exist. Copy one from GET /v1/models or the model list. |
404 with /v1/v1/ in the path | The API host ends in /v1. Change it to https://halfoff.dev. |
404 Unknown endpoint | AionUI is calling an API Half Off Dev doesn't serve, such as embeddings. Use Half Off Dev for chat and another provider for that feature. |
402 | The balance is empty or the key has hit its spend cap. See Billing. |
Any other status is explained in Errors.