FAQ

Frequently asked questions about Patter.

Getting started

What is Patter?

Patter is a local-first iOS language-learning app. You create AI contacts — each with a name, backstory, and personality — and text them. They reply only in the language you're learning. When you make a grammar mistake, a quiet correction appears below your message. No drills, no vocabulary decks, no sign-up required for BYOK.

What does BYOK mean?

BYOK stands for Bring Your Own Key. With BYOK, no developer-owned server is involved — you sign up directly with an AI provider (Google AI Studio, OpenAI, Anthropic, OpenRouter, Grok/xAI, or any OpenAI-compatible endpoint), get an API key, and paste it into the app. Messages go from your iPhone straight to the provider. The developer never sees your conversations or your key.

What is PatterAI? Do I need an API key?

PatterAI is an optional managed-AI subscription for people who don't want to manage their own API key. PatterAI requests are routed through a Cloudflare Worker operated by the developer — the Worker validates your subscription, tracks credits, and forwards the request to an AI provider. Message content is not logged or retained by the Worker. You can switch between BYOK and PatterAI at any time in Settings.

Which AI provider should I start with?

Google AI Studio is the easiest starting point — it has a generous free tier and requires no billing information to begin. If you run into rate limits (common with heavy use), OpenRouter with a small credit top-up gives you access to many models from one account. See all free and budget options →

Setting up an AI provider

How do I set up Google AI Studio?

1. Go to aistudio.google.com and sign in with your Google account.
2. Click Get API key → Create API key.
3. Copy the key and paste it into Patter under Settings → API Key.
4. Select Google AI Studio as your provider and choose a model (Gemini 2.5 Flash is a good default).

The free tier supports most models with per-minute and per-day request limits. See Google's rate limit documentation for current quotas per model.

How do I set up OpenAI?

1. Create an account at platform.openai.com.
2. Add a payment method under Billing and add some credits (a few dollars goes a long way).
3. Go to API keys → Create new secret key.
4. Copy the key and paste it into Patter under Settings → API Key.
5. Select OpenAI as your provider. Recommended models: gpt-4o-mini (fast and cheap) or gpt-4o (best quality).

OpenAI has no free tier on the API — you pay per token used. Conversation costs are typically fractions of a cent per exchange.

How do I set up Anthropic?

1. Create an account at console.anthropic.com.
2. Add a payment method and purchase credits.
3. Go to API Keys → Create Key.
4. Copy the key and paste it into Patter under Settings → API Key.
5. Select Anthropic as your provider. Recommended model: claude-haiku-4-5 (fast, affordable) or claude-sonnet-4-6 (higher quality).

How do I set up OpenRouter?

OpenRouter is a unified API that routes to dozens of AI providers — including Google, Anthropic, Meta, and Mistral — from a single account and key. It's the most flexible option.

1. Create an account at openrouter.ai.
2. Optionally add credits under Credits (or use the free tier — see below).
3. Go to Keys → Create Key.
4. In Patter, go to Settings → API Key, select OpenRouter as your provider, and paste your key.
5. Choose your preferred model from the model list.

Troubleshooting

Why am I being rate limited by Google?

Google AI Studio's free tier enforces per-minute (RPM) and per-day (RPD) limits on each model. These limits are quite low on the free tier — for example, Gemini 2.5 Pro is capped at just a few requests per minute on free accounts.

Patter sends your full conversation history with each message, which means even a short chat can count as multiple large requests. If you're hitting rate limits:

• Wait a minute and try again — per-minute limits reset quickly.
• Switch to a faster model with higher free limits, such as Gemini 2.5 Flash.
• Enable billing on your Google AI account at aistudio.google.com — paid usage has significantly higher limits.
• Switch to OpenRouter — even with free models, you're spread across different providers' limits.

Free and budget options

How do I use Patter for free with OpenRouter?

OpenRouter offers a selection of models completely free of charge — no credits required. These are marked with a :free suffix on the model ID (for example, meta-llama/llama-3.3-70b-instruct:free).

To use them, set up an OpenRouter account and API key as described above, then — when selecting a model in Patter — look for models with Free indicated. You can also browse the full list of free models at openrouter.ai/models.

What are the downsides of free models?

Free-tier models on OpenRouter work well for casual use, but there are trade-offs:

• Rate limits — free models are typically capped at 20 requests per minute and 200 per day.
• Slower responses — free requests are lower priority and may queue behind paid traffic during peak hours.
• Older or smaller models — free versions are usually not the latest or largest variant, which means lower fluency and less nuanced corrections.
• Smaller context windows — some free models accept fewer tokens, which can cause older parts of a long conversation to be dropped.
• No guarantees — free models can be removed or changed without notice.

For regular daily practice, adding a small credit top-up ($5–10) gives much better reliability and unlocks significantly better models.

Recommended models on OpenRouter

These are the models we recommend for language learning on OpenRouter. All offer strong multilingual fluency, good instruction following, and reliable in-character behaviour.

Model availability and pricing on OpenRouter can change. Check the OpenRouter model list for current status before committing to a model.

The app

What languages does Patter support?

Patter supports 11 languages with dialect precision: English (US/GB), Spanish (Castilian/Latin American), Portuguese (European/Brazilian), French (France/Canadian), German, Italian, Japanese, Mandarin, Korean, Russian, and Romanian.

What CEFR levels are supported?

A1 through C1. You can switch your level at any time mid-conversation — the AI persona's vocabulary, grammar complexity, and patience adjust immediately without resetting the conversation.

How do corrections work?

When you make a grammar or vocabulary mistake, a small note appears beneath your message showing what was wrong, the corrected form, and a one-line explanation. These corrections are generated by the same AI model handling your conversation — they are not a separate grammar-checking service.

Does Patter work offline?

No. Every message requires a live connection to your AI provider's API. Your past conversations are stored on your device and readable offline, but sending new messages requires an internet connection.

Can I use Patter on iPad?

Patter is designed for iPhone. It may run on iPad in iPhone compatibility mode, but the interface is not optimised for the larger screen.

Where is my data stored?

Conversations are stored locally on your device via SwiftData. API keys (BYOK) and any PatterAI credentials are stored exclusively in the iOS Keychain. With BYOK, messages go directly from your device to your chosen AI provider — no developer-owned server is involved. With the optional PatterAI plan, requests pass through a Cloudflare Worker that validates your subscription and tracks credits without retaining message content. See the Privacy Policy for full details.

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