AI Chat App With Your Own API Key on iPhone and Android

To use your own API key in an AI chat app on iPhone or Android, you need a third-party "bring your own key" app, because the official ChatGPT, Claude and Gemini apps sign you in to a subscription and have nowhere to paste a key. Create the key in the provider's developer console (OpenAI, Anthropic or Google), add some prepaid credit, paste the key into the app's API key screen, and pick a model. From then on the provider bills you per token at its API price. As of November 2026, Pal Chat (iPhone only), Chatbox and Oriveo (both phones) and Zemith (both phones plus the web) all do this.

Zemith is the one we'd pick if you want more than a chat window. On Zemith Plus ($15.99 a month) you add your OpenAI, Anthropic or Google key on the API Keys screen of the iPhone or Android app. Chats on that provider's models are billed to your provider account and use no Zemith credits, while every other model, plus web search, deep research, files and images, runs on your 1.5 million monthly credits. A key also opens that provider's top models: with an Anthropic key, Plus can chat with Claude 5.5 Opus, which on credits needs Pro.

TL;DR

• The official ChatGPT, Claude and Gemini phone apps don't accept API keys. An API key works only in apps built to take one.
• Keys come from platform.openai.com/api-keys, platform.claude.com/settings/keys and aistudio.google.com/apikey. OpenAI and Anthropic need prepaid credit first (OpenAI's minimum is $5).
• As of November 2026, Pal Chat is iPhone only (Pro $6.99), Chatbox is free with your own key on iOS and Android, Oriveo is free with your own key on iOS, Android and web, TypingMind has no native app, and BoltAI's phone app is still in beta.
• Zemith takes OpenAI, Anthropic and Google keys on Plus ($15.99/mo) and Pro ($29.99/mo) in its native iPhone and Android apps and on the web, with credits for everything else.
• A typical message (2,000 tokens in, 600 out) costs about 1 cent on Claude Sonnet 5.5 and 2 cents on Claude Opus 5.5 at Anthropic's API prices.

Which iPhone and Android apps take your own API key?

Checked on the App Store, Google Play and each vendor's site, November 14, 2026. Prices in US dollars.

Sources: Pal Chat on the App Store, Chatbox pricing and App Store listing, Oriveo pricing, TypingMind's buy page, BoltAI pricing and beta page. More detail on two of them: Chatbox pricing explained and TypingMind pricing explained.

How do I get an API key for ChatGPT, Claude or Gemini?

You create it in the provider's developer console, which is a separate account from your chat subscription. A ChatGPT Plus or Claude Pro subscription doesn't come with an API key or API credit. Here's where each one lives:

1. OpenAI (the models behind ChatGPT). Sign in at platform.openai.com/api-keys and create a secret key. Before real use, add a payment method and buy prepaid credit: the minimum purchase is $5, and auto-reload is switched on by default during setup, so turn it off if you want a hard ceiling. Since October 28, 2026, ChatGPT Pro and Business subscribers can claim up to $500 a month in API credits; Plus isn't included.
2. Anthropic (Claude). Create a key in the Claude Console at platform.claude.com/settings/keys, then buy credits on the Billing page. Purchased credits expire a year after purchase and aren't refundable. Claude Max, Ultra and Team plans now include monthly API credits ($100 on Max, $200 on Ultra) that expire each billing cycle; Free and Pro don't.
3. Google (Gemini). Create a key at aistudio.google.com/apikey. New users get a default Google Cloud project and key when they accept the terms. Google's API key guide says imported projects may need verification before the free tier works, and you can set up billing for the paid tier.

Each console shows the full key once. Copy it straight into a password manager or into the app, never into a chat message or a screenshot.

How do I add my API key in the Zemith app on iPhone or Android?

The labels below are the app's own. It takes about two minutes per provider.

1. Install Zemith from the App Store or Google Play and sign in. Adding keys needs Plus or Pro. On Free, the screen shows Upgrade to use your own keys instead.
2. Open the sidebar and tap the Settings gear. Under Preference, tap API Keys.
3. You'll see three rows: OpenAI, Anthropic and Google. Tap Add key next to the one you want.
4. Paste the key into the field (OpenAI keys start with sk-, Anthropic keys with sk-ant-, Google keys with AIza) and tap Test API key. Zemith asks the provider whether the key works and shows "Models it can use", for example Claude 5.5 Haiku, Claude 5.5 Sonnet and Claude 5.5 Opus.
5. Tap Save key. The row now reads "Anthropic key ••••1234" with an Enabled badge.
6. Start a chat and open the model picker. Models that will run on your key show a small key icon ("Runs on your API key").

Your key is stored encrypted and only its last four characters are ever shown. Tap the key's row to Disable it, Replace key or Remove it. While it's switched on, chats on that provider's models always use it, and the key always serves the exact model you picked. If the key stops working (revoked, out of credit, rate-limited), the chat stops with an error that says so; it never quietly switches to your Zemith credits. Switch the key off or remove it and those models go back to credits.

Because the key is saved to your account, not to one phone, it also works in Zemith on the web (Settings, then the API Keys tab) and on your other devices without pasting it again. The full list of supported models is on the bring your own API key page.

What does a chat on your own key cost?

Less than most people expect for text. Take a typical message where the model reads 2,000 tokens (your question plus earlier messages) and writes 600, priced at the providers' published rates in November 2026:

Prices from Anthropic's pricing page and OpenAI's pricing page. Long chats and pasted documents send more input tokens, so heavy use costs more.

In Zemith, those replies cost no credits. Tools you call inside the chat, such as web search and image generation, still use Zemith credits, and so do Creative Studio, Cloud runs and workflows. That's the split that makes the Plus plan interesting: the provider bills you for the model, and your 1.5 million credits go to everything else.

Which app should you use for your API key on a phone?

It depends on what you want besides the chat window.

Pal Chat is the cheapest polished option if you only use an iPhone. The app is free to download, Pro is $6.99, and it takes keys from more providers than anyone here, including OpenRouter and local models. There's no Android version, so it's out if your household or team mixes phones.

Chatbox costs nothing with your own key and runs on iOS, Android, desktop and the web. Its download guide asks new users to register on the website and claim a free licence before signing in. The hosted Chatbox AI plans (from $3.99 a month) are a separate product for people without keys.

Oriveo is also free with your own key on iPhone, Android and the web, and adds a cost estimate on each message. It's new: the Android app has been on Google Play since June 2026.

TypingMind works well in a browser and is a one-time purchase, but it has no phone app; its FAQ suggests adding the website to your home screen. BoltAI is a Mac app first, and its iPhone and Android apps are still in beta.

Zemith is for people who want the key and a full workspace in one place. What changes for you:

• One app on every device. Native iPhone and Android apps and the web, one account, the same chats, and the key added once.
• Keys and credits side by side. Put Claude on your Anthropic key and keep using Grok, DeepSeek, Kimi or Mistral on credits in the same chat history. Each key has its own on/off switch.
• Tools without more keys. Web search with sources, deep research, Word, Excel, PowerPoint and PDF files, image and video generation and plugins are built in. In a BYOK-only app, each of those is another API key and another bill, or it isn't there.
• Top models from Plus. With your own key, Plus can chat with Claude 5.5 Opus, GPT 6.1 Sol, GPT 6 Astra or Gemini 4 Argon, which on credits need Pro. If Opus is the reason you're here, using Claude Opus on your own API key has the full cost math.

A concrete workflow: on the train you paste two supplier quotes into a chat and ask Claude 5.5 Opus, on your Anthropic key, which one is the better deal. You then ask it to search the web for reviews of both suppliers and to turn its answer into a one-page Word summary. The Opus replies bill to Anthropic, the search and the file use credits, and when you open your laptop the chat and the file are waiting on the web.

Is it safe to put your API key in a phone app?

It's as safe as the app that holds it, so check where the key lives. TypingMind keeps keys in your browser's local storage, Oriveo says keys stay on your device for its own-key providers, and Pal Chat's App Store privacy label says the developer collects no data. Zemith stores your key on its servers, encrypted, because its servers make the model calls for you on every device, and it shows only the last four characters.

Whichever app you pick, a few habits cap the damage if something goes wrong:

• Create one key per app, so you can revoke one without breaking the others.
• Turn off auto-reload on OpenAI and Anthropic, or keep a small prepaid balance, so a leaked key can only spend what's there.
• Revoke the key in the provider's console if you lose the phone or stop using the app.

What Zemith doesn't do with your own key

Be clear on the limits before you pay. Zemith takes keys from OpenAI, Anthropic and Google only: no OpenRouter, no other providers, no local models, and no keys for image or video models. The Free plan can't add keys. There's also no key-only plan, so if you only ever chat with one provider, you pay $15.99 a month on top of your API bill. In that case, Chatbox or Oriveo (free with your key) or Pal Chat on iPhone is cheaper, and the full roundup of BYOK chat apps covers desktop options too.

How we compared

We read each app's App Store or Google Play listing and its official pricing page on November 14, 2026, and the providers' key, billing and pricing docs on the same day. The Zemith steps and labels come from the current iPhone and Android app. We didn't run speed or quality benchmarks, and in-store prices can differ by country.

Bottom line

For a pure chat client on one phone with your own key, Pal Chat (iPhone) or Chatbox and Oriveo (both phones) cost the least. If you want your OpenAI, Anthropic or Google key on a native iPhone and Android app that also does web search, deep research, files and images, with credits covering every other model, Zemith Plus at $15.99 a month is the better buy, and your key opens Claude 5.5 Opus on it without paying for Pro.