OpenCode Desktop Integration
Connect OpenCode Desktop to Claude and GPT models through Halfbill. No config files — just open Settings, connect, and start building.
OpenCode Desktop is the GUI desktop app version of OpenCode — an open-source AI coding agent with a full visual interface for managing providers, models, and sessions. Halfbill is a built-in provider, so setup takes under a minute with no config files required.
Looking for the CLI version? See the OpenCode CLI guide.
Two Built-In Providers
OpenCode ships two Halfbill entries, sharing one endpoint and one API key. Both accept a Halfbill key; the DevPass (Halfbill) entry lists canonical model IDs (for example claude-opus-5), which is the form to use with a Halfbill Code plan key.
Prerequisites
- OpenCode Desktop installed — download for Windows or macOS
- A Halfbill API key — sign up
Installation
Download OpenCode Desktop from opencode.ai/download and install it for your platform:
- macOS (Apple Silicon) —
.dmginstaller - macOS (Intel) —
.dmginstaller - Windows —
.exeinstaller
You can also install on macOS via Homebrew:
brew install --cask opencode-desktopSetup
Open Providers Settings
Launch OpenCode Desktop. Click the Providers section in the left sidebar under Server. You'll see the list of built-in providers:
Find Halfbill
Click Show more providers at the bottom of the list, or click + Connect on any entry to open the provider search. Type LLM in the search box — both Halfbill and DevPass (Halfbill) appear under "Other".
Select the one matching your key. You can connect both — they take the same key, and each contributes its models to the picker.
Enter Your API Key
OpenCode will show the Connect Halfbill dialog. Paste your Halfbill API key (starts with llmgtwy_) and click Continue.
Sign up or log in to your Halfbill dashboard and navigate to API Keys to get your key.
Select a Model
Once connected, open the model picker from the chat input bar. Type llm to filter Halfbill models and pick one, for example Claude Sonnet 5 or GPT-5.5.
Start Building
Select a model and start chatting. All requests route through Halfbill — you'll see usage, costs, and logs in your dashboard.
Why Use Halfbill with OpenCode Desktop
- Claude and GPT — Anthropic and OpenAI models at half list price
- One API key — No separate provider accounts to manage
- Cost tracking — See exactly what each session costs in your dashboard
- Response caching — Repeated requests hit cache automatically
Switching Models
You can switch models at any time from the model picker in the chat input bar. Click the current model name, type llm to filter to Halfbill models, and select a new one. The switch takes effect immediately for the next message.
Troubleshooting
Halfbill doesn't appear in provider list
Click Show more providers at the bottom of the Providers page to expand the full list, then search for "LLM".
Authentication errors
Make sure your API key starts with llmgtwy_ and is active. Check your dashboard to confirm the key is valid.
Models not loading after connect
Try disconnecting and reconnecting the provider from Settings > Providers. If models still don't load, check your internet connection and verify the key is valid.
View all available models on the models page.
Need help? Email support@halfbill.uk.
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