# Build brief — a focused alternative to ChatGPT

> **Verdict:** Not faithfully · **Buildability:** 21/100 · **Category:** AI Assistant
> **Source:** https://www.canitbevibecoded.com/chatgpt
> Independent editorial assessment from Can It Be Vibe Coded? Not affiliated with, endorsed by, or derived from ChatGPT. Verify current pricing and capabilities before acting.

## Context

**ChatGPT** — General AI assistant for writing, coding, research, images, and workflows. It currently costs $20/mo.

You can build a chat UI over APIs, but you cannot solo-recreate the model, multimodal stack, tools, memory/product layer, safety systems, and scale.

This brief describes a focused, single-operator replacement for the part of ChatGPT that is genuinely reproducible. It is deliberately narrower than the product it replaces, and it says so in writing. Build the useful core; do not pretend to have rebuilt the rest.

## What you are building

Build a chat interface that calls OpenAI/Anthropic/local models, stores conversations, and adds file upload/tools.

- Build a focused single-user workflow with real persistence, search, and export.
- A responsive interface with real empty, loading, success, and error states.

## Requirements

### Functional

- Hosted app.
- Vector store if retrieval.
- Auth/storage.
- Tool integrations.

### Data and integrations

- LLM API key or local model.

Each of these needs a real account, credential, or quota. Set them up before writing feature code.

### Non-functional

- Accessibility: semantic markup, labelled controls, visible focus, and reduced-motion support.
- Security: server-side secrets, validated input, and no credentials in the client bundle.
- Reliability: retries with backoff on external calls, and a clear failure state when a provider is down.
- Portability: the operator can export their data and leave without losing it.

## Implementation brief

Build me a personal chat client on the OpenAI and Anthropic APIs to replace the
text-chat part of ChatGPT Plus. Requirements:

- A local web app: Node + Express + better-sqlite3, one page with a streaming
  reply pane (SSE), a model picker, and a conversation sidebar.
- OpenAI and Anthropic keys in .env; system prompt editable per conversation.
- Conversations stored in SQLite with FTS5 search; export any thread to
  Markdown.
- File upload for text and PDF (pdf-parse); contents go straight into the
  context window, no vector database.
- A usage footer: tokens and estimated cost per conversation and per month,
  computed from the usage field in API responses, so I can compare real spend
  against the $20 flat fee.
- Localhost only. No accounts, no telemetry, everything stays on my machine
  except the API calls.
- Out of scope: image generation, voice mode, browsing agents, memory, and
  mobile apps. Do not attempt any of them; that gap is the subscription.
- README: where to get each key, links to current per-token pricing, and state
  plainly that this replaces text chat only, the frontier model itself cannot
  be rebuilt.

## Delivery standard

- Inspect the repository first, then write a short implementation plan before writing code.
- Deliver the smallest complete end-to-end workflow first; every primary control must work against persisted data.
- Use real validation and storage; never substitute fake dashboards, decorative controls, hard-coded success states, or mock integrations.
- Include responsive layouts plus genuine empty, loading, success, validation, and failure states.
- Keep secrets server-side in environment variables, provide .env.example, and never commit credentials or user data.
- Add structured logs around every external call and return actionable errors without leaking sensitive details.
- Write unit tests for the core logic and one automated test of the main user journey.
- Finish with a README covering setup, architecture, data location, backups, tests, deployment, and known limitations.

## Acceptance criteria

- [ ] A clean install starts the app using only the README and .env.example.
- [ ] The primary journey works from first visit through saved result, reload, edit, export, and deletion where applicable.
- [ ] Invalid input, missing configuration, provider failure, and an empty database each have a usable state.
- [ ] The interface works at 390px and 1440px, is keyboard navigable, and shows visible focus on every control.
- [ ] Tests, type checking, linting, and a production build all pass with no ignored failures.
- [ ] No part of the interface implies a live integration, security guarantee, or scale capability that was not actually built and verified.

## Non-goals

Do not build these, and do not claim to have replaced them:

- Frontier models.
- Multimodal features.
- Tool ecosystem.
- Reliability.
- Model quality and inference operations are part of the product.
- Reliability at the vendor's scale is an operations problem, not a prompt.

## What you still own after launch

- Secure credentials, rotate secrets, and handle provider rate limits.
- Run migrations, backups, restores, and dependency updates.
- Test the critical journey after every model, API, or hosting change.
- Monitor failures and fix the edge cases a first prompt will miss.

## Risk

**Operational risk.** The code is achievable; dependable data, integrations, and ongoing operations are the real cost.

Editorial confidence in this assessment: high. No independent one-shot implementation is linked yet.

## Prior art

Working open-source software you can read, fork, or borrow from before starting:

- [Open WebUI](https://github.com/open-webui/open-webui) — Open-source self-hosted AI chat interface for local and hosted models

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