OpenRouter

Language Den uses OpenRouter to access AI models for word analysis and flashcard generation. You need your own API key to enable AI features.

What Is OpenRouter?

OpenRouter is a service that provides unified API access to a wide range of AI models from providers including Anthropic, OpenAI, and others. Language Den uses OpenRouter so you can choose which model powers your AI features and pay only for what you use — there is no Language Den subscription or AI usage fee.

Getting an API Key

  1. Go to openrouter.ai and create a free account
  2. Navigate to Keys in your account dashboard
  3. Click Create Key and give it a name (e.g. “Language Den”)
  4. Copy the key — it starts with sk-or-
  5. Add credits to your account (a small amount goes a long way for vocabulary learning)
Info

OpenRouter charges per API call based on the model you choose. For typical vocabulary learning usage — adding a few words per day — costs are very low, often less than a cent per word depending on the model.

Adding Your Key to Language Den

  1. Open the Profile tab in Language Den (bottom-right)
  2. Tap API Keys
  3. Paste your OpenRouter key into the OpenRouter API Key field
  4. Tap Save

Your key is stored securely in the iOS Keychain and never leaves your device except when making API calls to OpenRouter.

Choosing a Model

Language Den supports four models via OpenRouter:

Model Speed Quality Best for
Claude 3 Haiku (default) Fast Good Everyday vocabulary additions
Claude 3.5 Sonnet Moderate Excellent Complex or nuanced vocabulary
GPT-4o Mini Fast Good Alternative to Haiku
GPT-4o Moderate Excellent Alternative to Sonnet

To change model, go to Settings → AI Model and select from the list.

Tip

Claude 3 Haiku and GPT-4o Mini are the most cost-effective choices for routine vocabulary work. Switch to a more capable model when you need higher-quality flashcards for difficult or nuanced words.

What Requires an API Key?

Feature Requires key
AI word analysis (meaning detection) Yes
AI flashcard generation Yes
Bulk flashcard generation Yes
Manual word entry No
CSV / Anki import No
Unsplash images Separate key

The app is fully functional for manual entry and import without an OpenRouter key.