NoteCalc is a handy calculator trying to bring the advantages of Soulver to the web.

Python quantitative trading strategies including VIX Calculator, Pattern Recognition, Commodity Trading Advisor, Monte Carlo, Options Straddle, Shooting Star, London Breakout, Heikin-Ashi, Pair Trading, RSI, Bollinger Bands, Parabolic SAR, Dual Thrust, Awesome, MACD

When the user wants to plan, design, or implement an A/B test or experiment. Also use when the user mentions "A/B test," "split test," "experiment," "test this change," "variant copy," "multivariate test," "hypothesis," "conversion experiment," "statistical significance," or "test this." For tracking implementation, see analytics-tracking.

Answer Engine Optimization (AEO) skill — optimize content to be cited by AI language models (ChatGPT, Perplexity, Claude, Gemini, Mistral) as authoritative sources. Distinct from SEO — AEO optimizes for citation in LLM-generated responses, not search rankings. Use when planning content for AI-first search audiences, auditing existing content for E-E-A-T signals, tracking which pages get cited by which LLMs, or building a citation-friendly content strategy. Triggers — 'AEO audit', 'optimize for ChatGPT', 'get cited by Perplexity', 'LLM citation strategy', 'answer engine optimization', 'content for AI search', 'E-E-A-T audit'. Output is a markdown audit report (default) or JSON for pipeline integration. Stdlib-only Python tools.

💸 Calculate estimated monthly costs of Google Cloud Platform products and resources via YAML files and CLI program (Linux, macOS, Windows)

:1234: Bits, bytes and general-purpose calculator

Fast Merkle-Patricia Trie (MPT) state root calculator and proof generator for prefix-sorted nibbles

Privacy-focused, free, open-source cryptocurrency tax calculator for multiple countries: it handles multiple coins/exchanges and computes long/short-term capital gains, cost bases, in/out lot relationships/fractioning, and account balances. It supports FIFO, LIFO, HIFO and it outputs in form 8949 format. It has a programmable plugin architecture

A cryptocurrency arbitrage opportunity calculator. Over 800 currencies and 50 markets.

:moneybag: International sales tax calculator for Node (offline, but provides optional online VAT number fraud check). Tax rates are kept up-to-date.

AI agent skills for Israeli tax, invoicing, VAT, and financial systems

A curated collection of reusable AI agent skills for Israeli government APIs, covering data queries, address validation, benefits, company lookup, drugs, and education.