Personal project · Oct 2026
yAI
A ChatGPT-style app and coding agent built on models I wire together myself: four hosted models that answer right away, a coding model on a cloud GPU that only exists while someone is using it, and a small model on my laptop's GPU.
## Models
The site is on Vercel. The default, yAI Lite (GLM-4.7-Flash on Z.ai), is fast and free, with DeepSeek V4.1 Flash behind it if Z.ai is busy. yAI Ultra Flash (DeepSeek V4.1 Flash) costs a fraction of a cent per reply, and yAI Ultra (DeepSeek V4 Pro) handles the hardest questions. Both run on DeepSeek's own API, where the repeated start of a prompt is cached and billed at a thirtieth to a fiftieth of the normal price, and everything is half price outside DeepSeek's peak hours; Kimi K3 on Modal takes over for yAI Ultra if DeepSeek is unavailable. yAI Q3.8 Max (Qwen3.8 Max, 2.4 trillion parameters) is a strong all-rounder on Modal. Anything with an image goes to free vision models instead: Gemini 3.5 Flash-Lite first, then Qwen 3.8 27B on Groq, then Gemini 3.8 Flash, each one handing over the moment its free quota runs out. Every reply's cost, at the price of whichever host answered, is added to a daily allowance per person in Upstash, so the bill can't run away, and admins can raise or lower each person's allowance.
A small model, yAI Q3.5, runs on my laptop's 6 GB GPU at up to 200 tokens per second: each question travels through a Cloudflare tunnel to a token-protected bridge in front of LM Studio, and it appears in the model menu whenever my PC is on.
It also makes images and videos on RunPod's serverless ComfyUI GPUs. Qwen-Image 2.1 creates pictures from a description or edits a photo you upload, and MiniMax H3 turns a prompt into a short video with sound. Everything goes through a safety filter and daily limits. Accounts, saved chats, images and videos are stored in Upstash Redis, so everything works even when my PC is off.
## The web app
The site has its own design with matching light and dark modes: warm neutrals, Geist type and one purple accent, and a sidebar that folds into a rail. On a phone it becomes an app that opens on the logo, with Chats, Projects and You tabs, bottom sheets for the model and the tools, and swipe-back navigation. A Search button looks the question up on the web, reads the top pages, and answers with numbered citations that link to each source. Projects keep files, PDFs and instructions together, so every chat started in one already has them. HTML, SVG and JavaScript in an answer open in a live preview that runs in a sandboxed frame. When a picture explains it better, answers include diagrams (flows, sequences, timelines) and charts drawn from the numbers, each with a table view and a download button. A usage page shows each person their messages, images, videos, searches and spend on the hosted models against the daily limits.
Deep research plans several searches, reads up to about fifteen sources over two rounds and has yAI Ultra write a cited report. Data analysis loads a CSV, Excel or JSON file into Python (Pyodide) right in the browser, so the file never leaves the device; the model writes pandas code, it runs there, and the charts appear under the answer. Memory keeps lasting facts you mention and lets you edit them. Voice mode takes dictation, reads any answer aloud, and holds a hands-free conversation. The canvas opens long writing and code in an editor beside the chat, with versions, "select a part and ask yAI to change it", and live HTML, JavaScript and Python runs. Ctrl K searches every saved chat and jumps to the exact message.
Answers can also call connected services for live, exact data: the weather, maps and directions, stock and crypto prices, sports scores, Wolfram Alpha, arXiv and Semantic Scholar papers, YouTube transcripts, your GitHub repositories and issues, UWaterloo LEARN due dates and course info, and webhooks to Discord, Slack or n8n. Live results show as cards, and watchers send a notification when a price drops or a page changes.
For school there's a study mode that tutors with hints and questions instead of answers, and a Study page that turns notes, a PDF or a chat into flashcards with spaced repetition and practice quizzes, with short answers graded by the model. A calendar and email tool reads a connected Google account and suggests Gmail drafts and calendar events as cards that are only saved when you press the button. Made images get an Edit button, one-tap edit ideas and a before/after slider, and the whole site installs as an app on a phone or laptop. Scheduled tasks run a prompt on their own every day, on weekdays, weekly or once (a morning news briefing, say), save the answer as a chat and send a notification to the phone.
Around it I built the parts a real service needs: an OpenAI-compatible public API with personal keys, counted against each person's limits; an admin People page with everyone's usage, per-person limits, account pausing and automatic flags for unusual use (bursts of requests, the same message over and over); and a What's new page where every release is numbered by its build.
## yAI Code
yAI Code brings the same models to the terminal: a coding agent like Claude Code that signs in with your yAI account and works inside your project folder. It reads and searches the files, edits them in place, and runs shell commands to build, test and lint the code. By default it asks before every file change and command, so nothing happens until you approve it. On DeepSeek it calls its tools natively, and it never reads the same lines of a file twice when they're still in front of it.
It also gets a model of its own: yAI 3 Coder (Qwen3 Coder 30B), a coding model with a 64K-token context and the one model still on a dedicated GPU. It runs on a 48 GB L40S on Modal with vLLM, keeps its weights on a Modal volume so a cold start loads them instead of downloading them again, and shuts down to zero when idle. It's a mixture-of-experts model that uses only 3 billion of its 30 billion parameters for each token, so it's quick for its size.
I benchmarked it inside yAI Code on six small Node.js tasks: fixing bugs, writing an LRU cache and an async retry helper from empty stubs, rewriting a CSV parser, and adding features across two files. Every task starts with failing tests, and the score is how many pass afterwards. yAI 3 Coder passed all 44 without touching a test file, and the simpler tasks took about 20 seconds each.
- 44/44tests passed
- 6/6tasks solved
- 0test files changed
It has three permission modes: ask prompts before any edit or command, auto-edit applies file changes automatically but still asks before running commands, and plan is read-only, so it explores the codebase and proposes a step-by-step plan without touching anything. You can @-mention specific files to point it at the right place, and each project folder keeps its own saved conversations, so picking up a project later resumes right where you left off.
It also handles the rest of the coding loop. /fix runs the tests and keeps fixing the code until they pass, and /fix watch reruns them on every save. /review has a second model review the uncommitted changes, and /commit writes the message and commits. It can see, too: /look screenshots the page on desktop and phone for a design review by a vision model, an @-mentioned mockup image becomes something the coder can build from, and /showcase records a demo video of the page. In /duo mode two models work together, one planning and reviewing while the other writes the code; /tutor gives hints instead of finished solutions, /share publishes a session at an unlisted link, and /undo reverts its last edit.
It runs as a full-window app so you always know what it's doing, what it needs and what you can press: a header on top, the conversation in the middle with the plan in a panel beside it, and the input box and keys at the bottom. A status pill says Ready, Working, Finished or Needs attention, approvals say what a command does and how risky it is and take a single key, and a finished task ends with a summary of tests, files and cost. It searches the web when it needs documentation, runs dev servers as background tasks, connects to MCP servers, and comes as a VS Code extension that opens every proposed edit as a diff. yai remote sends a task from my phone to my PC, and /clone rebuilds a page from a screenshot or a URL, then compares its result with the original and fixes the differences.
## /team and /crew
/team runs a whole team of agents. A lead model splits the task, a researcher looks up what a great version needs, an architect writes a contract of every shared name and a skeleton of every file, and up to eight builders work at the same time, each owning a feature. After them come a merger, yAI's own browser checks (it opens the page, gets past its menus, measures the frame rate, checks phone sizes and plays games for 30 seconds), a single QA agent, a fixer working from one merged to-do list, and a spec checker that scores the result against the request. A judge plays it, and the next round improves on what it saw, with a pause between rounds to try it yourself and say what to change. A watcher reads every agent's steps every 20 seconds, keeps their to-do lists accurate and redirects one that's going round in circles. A live board shows each agent's step, time and cost, and every run ends with a report page: a replay of the board, the score, screenshots, and a table of where the time and tokens went.
/crew came out of what /team taught me: on a game, one agent that holds the whole picture beat a team of builders working apart. So in /crew a single main builder builds the whole project itself, checking the page as it goes, and commissions helpers for the separate jobs (level data, sprites, sounds, tests, research) on yAI Lite or Ultra Flash; they work at the same time and report back to it. The same checks, fixes and rounds run after it. In the video, /team's fourteen agents built a Windows 95 style desktop with six apps from one prompt.
- JavaScript
- Node.js
- CLI agent
- Multi-agent
- Vercel
- Modal
- DeepSeek API
- Z.ai GLM
- Gemini API
- Groq
- Qwen3.8
- Kimi K3
- RunPod
- vLLM
- ComfyUI
- Upstash Redis
- MCP
- VS Code extension
- Headless Chrome
- Pyodide
- OpenAI-compatible API
- PWA
- Cloudflare Tunnel
- LM Studio
yAI is invite-only. The hosted models answer right away; yAI 3 Coder, images and videos can take a minute or two to start after a quiet stretch while their GPU wakes up.