A BYOK chat UI is the simplest category on this platform: paste your API key, start chatting. No managed subscriptions, no vendor deciding which model you get. The market is crowded, though, and the tools differ more than they first appear.
This guide covers the six most-used options in the BYOK community right now — NextChat, big-AGI, TypingMind, LobeHub, Chatbox, and BetterChatGPT — and tries to be honest about what each one is actually good for.
What separates a good BYOK chat interface from a generic one
Most BYOK chat UIs do the same core thing: they send your messages to a provider API and display the response. The differences that matter in practice are how your key is stored, which providers the app supports, how well the conversation context is managed, and whether the interface gets out of your way.
Key storage is the first thing to check. A well-designed app keeps your key in local browser storage or on-device — it never sends it to the app developer's server. Most tools on this list do this correctly, but it is worth verifying for anything you use for sensitive work.
- Key stored locally (not on the developer's server)
- Supports multiple providers, not just OpenAI
- Good conversation history and context management
- Clean enough to use for hours without friction
NextChat — the fast-starting default
NextChat (also known as ChatGPT-Next-Web) is the most widely deployed BYOK chat app in the world by a significant margin. It is a Next.js web app you can run in a browser, deploy to Vercel in two minutes, or install as a PWA on desktop. The setup is minimal and the interface is clean.
Its main strength is simplicity and breadth. It supports OpenAI, Anthropic, Google Gemini, Azure, and custom endpoints. The conversation sidebar is clear, prompt templates are easy to add, and the mobile experience is solid.
The weakness is that it does not go deep on any one feature. It does not have multi-model comparison, advanced persona management, or team features. If you want a capable daily driver and do not need anything special, NextChat is usually the right answer to try first.
big-AGI — when you want everything
big-AGI is the most feature-complete open-source BYOK chat UI available. It goes significantly beyond basic chat: multi-model conversations, beam mode for parallel model responses, personas with memory, voice input, image understanding, and a built-in diagram and code execution environment.
It supports more providers than almost anything else in this category. The interface is denser than NextChat, which is a deliberate tradeoff — this is a tool for people who want control and capability, not simplicity.
Self-hosting takes a bit more setup than NextChat, but it is well-documented. If you find yourself wanting features that NextChat does not have, big-AGI is the next place to look.
TypingMind — polished and worth paying for
TypingMind is the only commercial tool in this comparison. It is a one-time purchase rather than a subscription — Standard is $39, Extended is $79, and Premium is $99 (current list price; they run periodic promotions). The interface is notably more refined than any of the open-source options — better typography, cleaner settings panels, and thoughtful small interactions.
It supports all major providers, has a strong character and persona system, and stores everything locally. There is also a team/business version with shared prompt libraries.
The honest reason to choose TypingMind over the free options is polish. If you spend several hours a day in a chat interface and you care about the quality of the experience, the one-time cost is easy to justify. If you just need something functional, the free tools are perfectly good.
LobeHub — the most ambitious open-source option
LobeHub (the main product is LobeChat) is the most actively developed open-source BYOK chat interface. It has a plugin ecosystem, agent templates, MCP support, and a polished design that rivals commercial tools. The GitHub star count and release frequency are both high.
It supports BYOK for most major providers and also has a local model option via Ollama integration, which makes it technically a hybrid BYOK + BYOM tool. The web version works well; there is also a desktop app.
The main caveat is complexity. LobeHub is building toward a full AI platform, not just a chat interface. That is good if you want to grow into more advanced features. If you want something lightweight, that ambition can feel like overhead.
Chatbox and BetterChatGPT — solid alternatives worth knowing
Chatbox is a cross-platform desktop app (Windows, macOS, Linux) with a good native feel. It supports multiple providers, stores keys locally, and has clean conversation management. The main advantage over web-based tools is that it behaves like a real desktop app — it is in your dock, it opens quickly, it feels stable.
BetterChatGPT takes the opposite approach: maximum simplicity. It is a clean open-source web app with no feature bloat. Good conversation history, local key storage, basic provider support. It is the right choice if you want something minimal that just works and does not have a learning curve.
How to choose
Start with NextChat if you want something set up in under five minutes. Upgrade to big-AGI if you find yourself wanting multi-model comparison or advanced features. Try TypingMind if you care about polish and do not mind a one-time payment. Use LobeHub if you want agents and a plugin ecosystem. Use Chatbox if you prefer a native desktop app. Use BetterChatGPT if you want the simplest possible thing.
All six store your API key locally. All six support at least OpenAI and Anthropic. The differences are in feature depth, polish, and how much the interface gets out of your way.