⬡ NexusAPI

Production-ready · Multi-tenant · Credit-gated

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A fully-featured backend API platform with Google OAuth, JWT auth, organisation-level credit system, async job processing, and idempotency — all in one.

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9 Endpoints

JWT Authentication

OAuth Google SSO

∞ Multi-Tenant

ARQ Async Jobs

Platform

Everything you need, nothing you don't

Built with FastAPI · PostgreSQL · Redis · SQLAlchemy 2.0 · ARQ

◎

Google OAuth 2.0

One-click login with Google. Auto-creates organisations from email domains. First user per domain becomes admin, all others are members.

Auth

◈

JWT Authentication

Signed, stateless tokens with configurable expiry. Role-based access control with admin and member roles. Bearer token standard.

Security

◉

Ledger Credit System

Double-entry accounting with atomic deductions using SELECT FOR UPDATE row locking. Credits granted, deducted, and refunded with full audit trail.

Billing

◇

Multi-Tenant Isolation

Complete organisational data isolation. Each tenant owns their credit pool, job history, and user roster. No cross-tenant data leakage.

Architecture

○

Async Job Queue

Background processing with ARQ and Redis. Submit jobs, get an ID immediately, poll for results. Credits deducted upfront, automatically refunded on failure.

Processing

◆

Idempotency Keys

Safe retries on all product endpoints. Unique constraint enforced at the DB level — submit the same key twice, pay only once, every time.

Reliability

Documentation

API Reference

Base URL: http://localhost:8000 · All responses are JSON · Open Swagger UI →

Authentication 2 endpoints

GET /auth/google Initiate Google OAuth login flow Public

Redirects the browser to Google's OAuth consent screen. On approval, Google sends the browser back to /auth/callback with an authorization code.

Response

302 Redirect → accounts.google.com/o/oauth2/auth?...

GET /auth/callback Handle OAuth callback, return JWT token Public

Exchanges the Google authorization code for user info. Auto-creates an Organisation (from email domain) and User if this is a new login. First user per domain becomes admin; subsequent users are members. Returns a signed JWT.

200 · Success

{
  "access_token": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...",
  "token_type": "bearer"
}

401 · Error

{"detail": {"error": "google_auth_failed", "message": "..."}}

User 1 endpoint

GET /me Get current user's profile and organisation JWT Required

Returns the authenticated user's full profile and their organisation details. Use this to verify your token and retrieve user metadata.

200 · Success

{
  "user": {
    "id": "da9706bf-b44e-460e-a8c7-f4d6bf1025b1",
    "email": "user@company.com",
    "name": "Jane Doe",
    "role": "admin",
    "organisation_id": "7f751a8a-c2d9-4a7c-a508-a96c1eef89af",
    "created_at": "2026-01-01T00:00:00Z"
  },
  "organisation": {
    "id": "7f751a8a-c2d9-4a7c-a508-a96c1eef89af",
    "name": "Company",
    "slug": "company-com",
    "created_at": "2026-01-01T00:00:00Z"
  }
}

Credits 2 endpoints

POST /credits/grant Grant credits to your organisation

Admin Only

Adds credits to the organisation's ledger balance. Restricted to admin users. Creates a transaction record with the provided reason for full audit trail.

Request Body

{
  "amount": 100,       // positive integer, required
  "reason": "string"   // 1–500 chars, required
}

200 · Success

{
  "message": "Granted 100 credits",
  "balance": 100,
  "transaction_id": "fe4a9ba0-531a-4e12-a9ad-11d5ae5780cf"
}

403 · Forbidden (non-admin)

{"detail": {"error": "forbidden", "message": "This action requires admin privileges."}}

GET /credits/balance Get balance and last 10 transactions JWT Required

Returns the current credit balance (computed from the full ledger) and the 10 most recent transactions, ordered newest first.

200 · Success

{
  "organisation_id": "7f751a8a-c2d9-4a7c-a508-a96c1eef89af",
  "balance": 275,
  "recent_transactions": [
    {
      "id": "d02b2ca6-2e14-4f76-afb6-0bfe819a23cd",
      "amount": -25,
      "reason": "API call: /api/analyse",
      "created_at": "2026-03-02T10:38:42Z",
      "user_id": "da9706bf-b44e-460e-a8c7-f4d6bf1025b1"
    }
  ]
}

Products 3 endpoints

POST /api/analyse Synchronous text analysis

JWT Required 25 credits

Performs synchronous text analysis. Deducts 25 credits atomically using SELECT FOR UPDATE. Accepts an optional Idempotency-Key header — same key returns the cached result without additional charges.

Request Headers & Body

Authorization: Bearer <token>
Idempotency-Key: <unique-key>   // optional

{
  "text": "string"    // 10–2000 characters, required
}

200 · Success

{
  "result": "Analysis complete. Word count: 9. Unique words: 8.",
  "credits_remaining": 275
}

Error Responses

402  {"error": "insufficient_credits", "balance": 0, "required": 25}
401  {"error": "authentication_required", "message": "..."}
422  {"error": "validation_error", "message": "body → text: ..."}

POST /api/summarise Async text summarisation job

JWT Required 10 credits

Submits a background summarisation job via ARQ/Redis. Deducts 10 credits immediately. Returns a job_id — poll /api/jobs/{job_id} for results. Credits are automatically refunded if job fails to enqueue.

Request Body

{
  "text": "string"    // 10–2000 characters, required
}

200 · Success

{
  "job_id": "9d767976-470b-40f0-855e-0f72efded6a2",
  "credits_remaining": 240
}

GET /api/jobs/{job_id} Poll async job status and result JWT Required

Returns the current status of a job. Tenant-isolated — only the organisation that created the job can retrieve it. Returns 404 for unknown or cross-tenant job IDs.

200 · Success

{
  "job_id": "9d767976-470b-40f0-855e-0f72efded6a2",
  "status": "pending",    // pending | running | completed | failed
  "result": null,         // string when completed
  "error": null,          // string when failed
  "created_at": "2026-03-02T10:38:42Z"
}

404 · Not Found

{"detail": {"error": "job_not_found", "message": "No job found with ID ..."}}

System 1 endpoint

GET /health System health and database status Public

Returns 200 if the API is running and the database is reachable. Returns 503 if the database connection fails. Suitable for load balancer health checks.

200 · Healthy

{
  "status": "healthy",
  "database": "reachable",
  "timestamp": "2026-03-02T10:38:42.079590+00:00"
}

503 · Unhealthy

{"status": "unhealthy", "database": "unreachable", "timestamp": "..."}

Overview

Credit Balance

—

Total Granted

—

Total Spent

—

Transactions

—

Recent Transactions

No transactions yet

Credits

Current Balance

—

Grant Credits Admin Only

Amount

Reason

Transaction History

No transactions yet

Text Analysis

25 credits / call Balance: —

Input Text (10–2000 characters)

0 / 2000

Idempotency Key (optional — prevents double-charges on retry)

Result

Text Summarisation

10 credits / job Balance: —

Summarise creates an async background job. You receive a job ID instantly — switch to the Jobs tab to poll for the result.

Input Text (10–2000 characters)

0 / 2000

Idempotency Key (optional)

Job Created

Jobs

Look Up a Job

Job Status

Session Jobs Jobs created this session

No jobs created yet in this session

Build on NexusAPI.Ship faster.

Everything you need, nothing you don't

Google OAuth 2.0

JWT Authentication

Ledger Credit System

Multi-Tenant Isolation

Async Job Queue

Idempotency Keys

API Reference

Overview

Credits

Text Analysis

Text Summarisation

Jobs

Build on NexusAPI.
Ship faster.