# Overview

nLight.fit is a personal fitness and life tracking platform with an AI coach attached to it.

The tracking half is deliberately plain: a spreadsheet-style ledger where you confirm your day. Did you wake at seven, take your vitamins, read, train, eat well, weigh in. The coaching half is not plain at all — it reads that ledger in full, alongside your WHOOP data, your bloodwork, your genetics and everything you have told it in past conversations, and answers questions grounded in what actually happened rather than in general advice.

The central idea is that a coach is only as good as its memory. Most AI fitness tools summarise your history into a paragraph and reason from that paragraph. This one keeps the record at full resolution and retrieves against it.

## What it does

**A commitment ledger.** One row per day, one column per thing you track. Standard columns for habits, fitness, and nutrition; custom columns for whatever else matters to you. Daily, weekly or monthly check-in rhythms, depending on how you want to work.

**An AI coach.** Conversational, streaming, and grounded in your data. It classifies what you are asking, decides how much history and how much reasoning the question warrants, retrieves the relevant days and summaries, and calls tools when it needs a precise number rather than a recollection.

**A voice agent.** The same coach over a real-time voice connection, with modes for open conversation, hands-free data entry, and guided onboarding.

**Health integrations.** WHOOP recovery, sleep and strain synced automatically. Bloodwork panels extracted from PDF lab reports. Methylation genetics as a one-time profile that explains mechanisms rather than tracking a trend.

**A correlation engine.** Runs through the day across every module — habits, nutrition, wearables, labs, genetics — with partial-correlation controls and multiple-testing correction, so what surfaces as a pattern has survived some scrutiny.

**An MCP server.** Read-only access to all of it from Claude, Cursor, or any MCP client, using the same tool handlers the in-app coach uses.

## Who it is for

Someone who already tracks, or wants to, and is frustrated that the data never turns into an answer. The platform assumes you will log honestly and consistently; almost everything interesting it does depends on having a real history to reason over.

## Availability

**Open signup.** Anyone can create a free account — no card, no waitlist, no approval step. Registration takes a username and a password and signs you straight in.

**Two plans.** Free covers the whole tracking product and gives you the coach on the same frontier model, thinking over your last 60 days. Member is $50/year, tax included, and is the tier that funds frontier-model intelligence on your full record — no history horizon, highest reasoning, mission analysis, expanded voice. What that actually changes, with examples, is on [membership](/docs/membership). Upgrade from [Pricing](/#pricing) or from Settings in the app. Checkout is attached to your signed-in account; a public Stripe link is never used.

Create an account at [nlight.fit/app](/app).

## How it is built

A short version, because it explains some of the behaviour you will encounter:

- **Vercel serverless functions** for the backend, **MongoDB Atlas** as the single source of truth. There is no client-side cache of your data; every change is written immediately and every read comes from the database, so two devices never disagree.
- **xAI Grok** for coaching and extraction, **xAI Realtime** for voice, **VoyageAI** for embeddings and reranking.
- **Hybrid retrieval** — vector search and full-text search fused, then reranked — so a question about something you wrote eight months ago can actually find it.
- **Background cron workers**, split by cost, that compute summaries, personal records, correlations and insights ahead of time, so the coach reads a precomputed answer instead of deriving one mid-conversation. See [when things run](/docs/analytics#when-things-run).

The [architecture](/docs/data-model) and [security](/docs/security) pages go further.

## Where to go next

- [Quickstart](/docs/quickstart) — from account to first coached conversation
- [Membership](/docs/membership) — why $50/year, and what higher reasoning changes
- [Concepts](/docs/concepts) — the vocabulary the rest of the docs assumes
- [The ledger](/docs/ledger) — how daily tracking actually works
- [MCP server](/docs/mcp) — connect Claude or Cursor to your own data
- [Docs assistant](/docs/docs-assistant) — the public overlay that will walk you here