DayBreak: A Self-Hosted AI Stock Analysis Tool
An open-source tool providing deterministic stock briefs without AI-generated numerical hallucinations.
1Deterministic Financial Analysis
DayBreak is an open-source, self-hosted tool designed for US equity investors seeking calm, data-driven morning briefings. Unlike standard AI applications, it ensures that every numerical value is computed deterministically using TypeScript. The platform avoids AI-generated hallucinations by separating raw data processing from the natural language generation layer of the system.
2Strict AI Guardrails
The system utilizes a zero-trust validation mechanism to maintain data integrity. The Gemini model receives a verified fact sheet and returns JSON output, which is then parsed using Zod. If the AI attempts to invent numbers, provide investment advice, or predict future prices, the system automatically rejects the output and reverts.
3Contextual Market Explanations
DayBreak explains daily stock movements by comparing performance against the broader market, specifically the SPY index and relevant sector ETFs like XLK or XLF. By analyzing 20-day volume ratios and date-matched news headlines, the tool classifies sessions as market-wide, sector-wide, or company-specific, providing users with clear, actionable context for price changes.
4Technical Indicator Suite
The platform includes a comprehensive library of technical indicators calculated directly in TypeScript. Users can access 20, 50, and 200-day simple moving averages, Wilder’s RSI, MACD, and Bollinger Bands. These tools are integrated into an interactive five-year chart, allowing investors to visualize historical price patterns and volatility metrics without relying on external black-box providers.
5Backtested Signal Scoring
DayBreak computes a signal hint score ranging from -100 to +100, representing a spectrum from strong sell to strong buy. This scoring rule is backtested against the stock’s historical data to demonstrate how the signal would have performed in the past, offering users a transparent view of the strategy's historical efficacy.
6Infrastructure and Deployment
Built with Next.js 15, React 19, and PostgreSQL, the tool is designed for deployment on a single Ubuntu VPS via Docker Compose or Coolify. It includes robust health monitoring, such as failure alerts and a dead-man's switch, ensuring that users receive their morning briefs reliably without constant manual server maintenance or oversight.
7Data Source Integration
The application aggregates financial data from multiple providers including Financial Modeling Prep, Finnhub, and Yahoo Finance. All fundamental data, such as P/E ratios, EPS, and dividend yields, is cached in a local Postgres database. This architecture minimizes API dependency while ensuring that the core analysis remains grounded in verified, real-time market data.
8Educational Purpose Only
DayBreak is strictly an informational tool intended for educational purposes and does not constitute financial or legal advice. Because technical indicators and backtests describe past performance, they cannot predict future market outcomes. Users are encouraged to perform their own research and consult qualified professionals before making any significant investment decisions.
Original article: Hacker News: Show HN — DayBreak: A Self-Hosted AI Stock Analysis Tool