Crypto Portfolio Tracker REST API

A highly optimized, asynchronous FastAPI engine for tracking cryptocurrency asset holdings, transaction history, and real-time profits and losses (P&L).

Performance Benchmarks

To ensure high-throughput capabilities and profile latency under execution stress, the REST API engine was benchmarked under two distinct profiles using an in-memory SQLite database and a mocked CoinGecko pricing handler to isolate core framework overhead.

Single Load Performance (50 Requests)

Below is the latency profile representing request processing time under a standard single load sequence:

• Database reads (live pricing check and portfolio aggregates) average under 1.5ms.
• Write actions (adding a holding with DCA computation) process in 2.6ms.

Multi-Load Comparison (10, 50, and 250 requests)

The chart below illustrates how performance profiles scale across varying transaction request loads:

• Read Operations: Query operations such as GET Live Price and GET Portfolio Summary scale flatly and complete in under ~1.5ms even under high loads.
• Write Operations: Holdings updates (POST Buy Holding) process in ~2.6ms with full validation.
• Security Checkpoints: Auth routines (POST Register and POST Login) are subject to Bcrypt CPU-bound operations (designed for security) taking ~220ms per cycle, while the surrounding HTTP routing adds zero noticeable overhead.

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Architecture

Below is the high-level architecture diagram of the REST API engine:

graph LR
    Client[Client Request] --> AuthRouter[Auth Router]
    Client --> HoldingsRouter[Holdings Router]
    Client --> PortfolioRouter[Portfolio Router]
    Client --> PricesRouter[Prices Router]
    
    AuthRouter --> AuthValidator[JWT Sign/Verify]
    HoldingsRouter --> DCAEngine[DCA Engine]
    PortfolioRouter --> ValEngine[Valuation & P&L Engine]
    
    AuthValidator --> DB[(PostgreSQL DB)]
    DCAEngine --> DB
    
    ValEngine --> CoingeckoClient[CoinGecko Service]
    PricesRouter --> CoingeckoClient

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Setup and Quickstart

Prerequisites

Ensure a local PostgreSQL instance is running with a database named crypto_tracker:

CREATE DATABASE crypto_tracker;

1. Installation

Set up a Python 3.12 virtual environment and install requirements:

python3.12 -m venv venv
source venv/bin/activate
pip3 install -r requirements.txt

2. Configuration

Copy .env.example to .env and verify the settings:

cp .env.example .env

Apply database migrations:

alembic upgrade head

3. Execution

Start the live development server:

uvicorn app.main:app --reload

Run the automated test suite:

PYTHONPATH=. pytest -v

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API Interface

Authentication

• POST /api/v1/auth/register - Registers a new user.
• POST /api/v1/auth/login - Authenticates and issues a JWT token.

Holdings

• POST /api/v1/holdings - Adds or updates token holdings (triggers the DCA recalculator).
• GET /api/v1/holdings - Fetches the current user's holding list.
• DELETE /api/v1/holdings/{holding_id} - Sells/deletes a holding.

Portfolio

• GET /api/v1/portfolio/summary - Aggregates holding quantities, cost, and live P&L.
• GET /api/v1/portfolio/history - Returns the complete audit list of buy and sell transactions.

Prices

• GET /api/v1/prices/{coin_id} - Queries live USD pricing from CoinGecko (features tenacious retries and caching policies).