Explore standalone interactive web calculators, financial forecasting engines, smart shopping deal trackers, and simulation tools designed to assist in long-term personal wealth planning, mortgage analytics, and real estate investment decisions.
All tools in this collection are 100% client-side, zero-backend, privacy-first single-page web applications. Source code is open-source and available on GitHub at thanhtrixx/html-standalone-tools.
1. Personal Finance & Savings Predictor
An interactive personal finance and multi-horizon wealth simulator that models net worth trajectories, forecasts salary growth, simulates compound interest across tiered deposit pools, and tracks savings goals with daily resolution.
Key Capabilities & Highlights
- Daily Resolution Compounding Engine: Computes high-precision daily compound interest across diverse deposit accounts, flexible savings, and liquid funds.
- Multi-Tier Savings Pools & Auto-Term Allocation: Define liquid cash pools and automatically sweep surplus funds into term deposits when surpassing user-defined cash thresholds.
- Salary Trajectory & Bonus Scheduling: Model career salary progression, 13th-month bonuses, and mid-year performance incentives with customizable calendar payout months.
- Inflation & Real Purchasing Power: Seamlessly toggle between nominal wealth metrics and real, CPI inflation-adjusted net worth figures.
- Goal Tracking & Milestone Visualizer: Set multi-million / multi-billion savings targets and visualize progress rings along with projected achievement dates.
- Side-by-Side Scenario Comparison (A/B): Compare two financial strategies side-by-side (e.g. aggressive saving vs. conservative spending) with real-time differential deltas.
- Sensitivity Matrix Heatmap: Interactive 2D matrix visualizing wealth outcomes against varying investment yields and inflation rates.
- AI Financial Health Dossier: Generate rich, structured markdown dossiers ready to copy into ChatGPT or Claude for personalized financial coaching and optimization advice.
- CSV Data Management: Built-in tabular editor to import, manage, edit inline, and export savings portfolio datasets.
- Privacy-First & Shareable: Zero server dependencies; export high-resolution chart images/PDFs and share simulation states via compressed URL hashes.
Direct Links:
2. Buy vs. Rent Home Comparison
A mathematical real estate decision engine that evaluates whether buying a home or renting and investing the financial difference creates superior long-term wealth over a 5 to 30-year horizon.
Key Capabilities & Highlights
- Dual-Mode Mortgage Amortization: Simulate both Linear Principal (DΖ° nợ giαΊ£m dαΊ§n β equal principal installments with declining interest) and Fixed EMI (NiΓͺn kim cα» Δα»nh β constant total monthly payment).
- Teaser Rate to Floating Rate Dynamics: Model promotional introductory interest rates (first 1β3 years) smoothly transitioning to market floating rates.
- Comprehensive Acquisition & Sunk Cost Breakdown: Quantifies registration taxes (0.6%), notary costs, and initial interior fit-out against pure sunk costs (loan interest, maintenance fees, HOA dues, property depreciation).
- Opportunity Cost & Investment Compounding: Accurately tracks the renter’s initial capital (down payment differential) and monthly cashflow surplus invested across savings deposits, balanced portfolios, or equity/ETF index funds (5.5% β 10.5%+).
- Net Realizable Equity: Calculates real net worth upon property sale after factoring in transaction friction (brokerage commission, 2% personal income tax, notary fees).
- Valuation & Yield Indicators: Real-time Price-to-Rent Ratio (PRR) and Gross Rental Yield indicators with health status benchmarks.
- Dynamic Crossover / Breakeven Point: Identifies the exact crossover year where homeownership equity overtakes the renter’s investment portfolio.
- 2D Sensitivity Matrix Heatmaps: Interactive heatmaps cross-referencing property appreciation rates (2%β12%) with equity investment returns (4%β14%).
- Pre-Configured Strategic Personas: Instant preset evaluation for Urban Condos (HN/HCMC), Suburban Landed Houses, FIRE Optimizers, and Short-term Expats.
- Transparent Mathematical Methodology: Live LaTeX formula breakdown (KaTeX) with live numerical substitution traces and an integrated financial glossary.
- AI Strategic Dossier: Generate structured markdown dossiers for AI financial advisory.
Direct Links:
3. Smart Buy-List & Unit Price Tracker
A mobile-first, standalone PWA grocery shopping list and price intelligence application designed for in-aisle package size comparisons, multi-store purchase tracking, unit price normalization ($/kg, $/L, $/ea), and historical deal rating scoring.
Key Capabilities & Highlights
- Unit Price Normalization Engine: Automatically normalizes item package prices across mass (kg, g, lb, oz), volume (L, ml, gal, fl oz), and discrete count units (ea, pk, box, can, bunch) for true apples-to-apples price comparison.
- In-Aisle Package Comparator: Live side-by-side comparison modal between package sizes (e.g. standard vs. bulk pack, different brands) calculating exact percentage savings and unit price differences in real-time, with 1-click winner adoption.
- Historical Purchase Ledger & Price Intelligence: Automatically records completed trip items with timestamp, store, paid price, and unit price into an indexed historical purchase ledger.
- Deal Scoring Badges & Sparklines: Real-time deal classification against historical purchases (Great Deal, Fair Price, Price Spike, New Item) with visual price sparkline trendlines.
- Two-Phase Trip Workflow (Planning & In-Store Buy Mode): Distinct workflows for pre-trip grocery planning with category/aisle organization and focused in-store shopping with live spend tally, progress bar, and unchecked item rollover management.
- Multi-Store & Aisle Grouping: Filter and group grocery items by aisle category (Produce, Dairy & Eggs, Meat & Seafood, Pantry, Bakery, Frozen, Beverages, Household, Personal Care) or by target store (Costco, Trader Joe’s, Supermarket, Local Market).
- PWA & Offline-First Storage: Progressive Web App with service worker caching, offline capability, IndexedDB storage with local storage fallback, and zero server or login dependencies.
- Peer-to-Peer List Sharing & Backup: Share shopping lists instantly via compressed URL links, dynamic QR codes, native OS share sheets, or JSON backup import/export with intelligent list merging.
- Multi-Currency & Bilingual Support: Built-in toggle for 7 major global currencies (USD, VND, EUR, GBP, JPY, AUD, CAD) and full English / Vietnamese bilingual UI localization.
Direct Links:
Open Source & Contribution
All web applications in this section are released as open-source software under the MIT License. They run entirely in your web browser with zero tracking, cookies, or backend storage requirements.
- GitHub Repository: https://github.com/thanhtrixx/html-standalone-tools
- Offline Usage: You can clone the repository and run any tool locally by opening the
index.htmlfile in any modern web browser. - Feedback & Contributions: Bug reports, feature suggestions, and pull requests are warmly welcomed via GitHub Issues and PRs.