# Vortenza > Free online tools and calculators for developers, freelancers, and small business owners. AI cost estimation, tax calculators, finance planners, developer utilities, email deliverability tools. All free, no signup required. ## AI Cost Tools - [AI Token Counter](https://www.vortenza.com/tools/ai-token-counter): Count tokens for GPT-4o, Claude, and Gemini. Estimate AI prompt cost. - [OpenAI API Cost Calculator](https://www.vortenza.com/tools/openai-cost-calculator): Estimate OpenAI API costs by model and monthly volume. Covers GPT-4o and GPT-5. - [Claude API Cost Calculator](https://www.vortenza.com/tools/claude-cost-calculator): Calculate Anthropic Claude API costs by model. Covers Opus, Sonnet, Haiku. - [AI Prompt Cost Estimator](https://www.vortenza.com/tools/ai-prompt-cost-estimator): Paste any prompt to estimate cost across GPT-4o, Claude, Gemini, and DeepSeek. - [AI Prompt Library](https://www.vortenza.com/tools/ai-prompt-library): 100+ free AI prompt examples for ChatGPT, Claude, and Gemini, searchable by category. ## SEO & AI Writing Tools - [AI Humanizer](https://www.vortenza.com/tools/vortenza-humanizer): Transform AI-generated text into human-sounding writing. Passes GPTZero, Turnitin, Originality.ai. - [AI Writer](https://www.vortenza.com/tools/vortenza-writer): Generate original human-style articles with no AI detection patterns. - [AI Detection Checker](https://www.vortenza.com/tools/ai-detection-checker): Check if text is flagged as AI-written by GPTZero, Turnitin, or Originality.ai. - [Plagiarism Checker](https://www.vortenza.com/tools/plagiarism-checker): Check content for plagiarism with n-gram analysis. No word limit, no signup. ## Developer Tools - [JSON Formatter & Validator](https://www.vortenza.com/tools/json-formatter): Beautify, minify, and validate JSON. Syntax highlighting, runs in browser. - [Regex Tester](https://www.vortenza.com/tools/regex-tester): Test regex with live match highlighting and capture group inspection. - [Base64 Encoder & Decoder](https://www.vortenza.com/tools/base64-encoder): Encode and decode Base64. Supports text, files, and URL-safe mode. - [URL Encoder & Decoder](https://www.vortenza.com/tools/url-encoder): Encode and decode URLs. Parse components and build query strings. - [JWT Decoder](https://www.vortenza.com/tools/jwt-decoder): Decode JWT tokens. View claims, check expiry, get security analysis. - [SQL Formatter](https://www.vortenza.com/tools/sql-formatter): Format SQL queries. Supports MySQL, PostgreSQL, SQLite, SQL Server. - [Markdown to HTML](https://www.vortenza.com/tools/markdown-to-html): Convert Markdown to HTML with live preview. Full GitHub Flavored Markdown support. - [Cron Job Builder](https://www.vortenza.com/tools/cron-job-builder): Build cron expressions visually. See next 5 run times, plain-English explanations. - [CSS Gradient Generator](https://www.vortenza.com/tools/css-gradient-generator): Generate linear, radial, conic CSS gradients with live preview and presets. - [Unit Converter](https://www.vortenza.com/tools/unit-converter): Convert length, weight, temperature, volume, area, speed. Metric and imperial. ## Finance Calculators - [Mortgage Payment Calculator](https://www.vortenza.com/tools/mortgage-payment): Monthly payment and full amortization breakdown. - [Compound Interest Calculator](https://www.vortenza.com/tools/compound-interest): Savings growth with contributions and APY over time. - [Freelance Rate Calculator](https://www.vortenza.com/tools/freelance-rate-calculator): Hourly rate calculation accounting for taxes, unpaid hours, business costs. 10 countries. - [Salary to Hourly Calculator](https://www.vortenza.com/tools/salary-to-hourly): Annual salary to hourly, daily, weekly, monthly. After-tax calculations. - [Net Worth Calculator](https://www.vortenza.com/tools/net-worth-calculator): Net worth with US median comparison by age. Assets vs liabilities. - [Inflation Calculator](https://www.vortenza.com/tools/inflation-calculator): Purchasing power using US CPI data 1913-2026. - [Invoice Generator](https://www.vortenza.com/tools/invoice-generator): Professional freelance invoices. Download print-ready. No signup. - [Emergency Fund Calculator](https://www.vortenza.com/tools/emergency-fund-calculator): Emergency fund target based on expenses, income type, risk factors. - [Debt Snowball vs Avalanche Calculator](https://www.vortenza.com/tools/debt-snowball-calculator): Compare both debt payoff methods side by side with real numbers. - [Freelance Contract Generator](https://www.vortenza.com/tools/freelance-contract-generator): Freelance contract covering scope, payment, IP ownership, termination. ## Tax Calculators - [Federal Income Tax Estimator](https://www.vortenza.com/tools/federal-income-tax): 2026 federal income tax with brackets and deductions. All filing statuses. ## Email Tools - [Email Deliverability Checker](https://www.vortenza.com/tools/email-deliverability-checker): Domain deliverability score 0-100. Validates SPF, DKIM, DMARC records. - [Email Spam Checker](https://www.vortenza.com/tools/email-spam-checker): Spam trigger words, formatting issues, deliverability risk analysis. - [Email Duplicate Checker](https://www.vortenza.com/tools/email-duplicate-checker): Remove duplicates from lead lists. Upload CSV files. - [Cold Email Subject Tester](https://www.vortenza.com/tools/cold-email-subject-tester): Subject line spam score, length check, open rate potential. - [SPF DKIM DMARC Checker](https://www.vortenza.com/tools/spf-dkim-dmarc-checker): DNS record validation with color-coded results and plain-English explanations. - [DMARC Generator](https://www.vortenza.com/tools/dmarc-generator): Generate valid DMARC TXT records with explanations for every setting. ## Guides - [What Is an AI Token](https://www.vortenza.com/guides/what-is-an-ai-token): Plain-language explanation of AI tokens, context windows, and API pricing. - [OpenAI API Pricing 2026](https://www.vortenza.com/guides/openai-api-pricing-2026): Complete GPT-4o and GPT-5 pricing guide with real cost scenarios. - [Claude API Pricing 2026](https://www.vortenza.com/guides/claude-api-pricing-2026): Complete Anthropic Claude pricing with model comparison. - [Gemini API Pricing 2026](https://www.vortenza.com/guides/gemini-api-pricing-2026): Gemini 2.5 Pro, Flash, and Flash-Lite token costs and free tier limits. - [LLM Cost Comparison 2026](https://www.vortenza.com/guides/llm-cost-comparison-2026): GPT-4o vs Claude vs Gemini vs DeepSeek per-token prices compared. - [ChatGPT vs Claude vs Gemini vs DeepSeek 2026](https://www.vortenza.com/guides/chatgpt-vs-claude-vs-gemini-vs-deepseek-2026): Head-to-head comparison for writing, coding, and research. - [ChatGPT Plus vs Claude Pro vs Gemini Advanced](https://www.vortenza.com/guides/chatgpt-plus-vs-claude-pro-vs-gemini): Which $20/month AI subscription is worth it. - [AI Detectors Are Guessing](https://www.vortenza.com/guides/ai-detectors-are-guessing): Why AI detection tools produce inconsistent results. - [How to Bypass AI Detection 2026](https://www.vortenza.com/guides/how-to-bypass-ai-detection-2026): What actually works for making AI text undetectable. - [Prompt Engineering Guide 2026](https://www.vortenza.com/guides/prompt-engineering-guide-2026): Techniques that improve AI output quality in 2026. - [Freelance Hourly Rate Calculator Guide](https://www.vortenza.com/guides/freelance-hourly-rate-calculator-2026): The formula for calculating a freelance rate that covers taxes and unpaid time. - [Freelance vs Salary Comparison 2026](https://www.vortenza.com/guides/freelance-vs-salary-comparison-2026): Real financial comparison including taxes and hidden costs. - [Freelance Contract Guide 2026](https://www.vortenza.com/guides/freelance-contract-guide-2026): Scope, kill fees, revision limits, and client pushback strategies. - [Freelance Invoice Guide 2026](https://www.vortenza.com/guides/freelance-invoice-guide-2026): How to invoice as a freelancer, payment terms, and follow-up strategy. - [Self-Employment Tax Guide 2026](https://www.vortenza.com/guides/self-employment-tax-guide-2026): 15.3% SE tax explained, calculated, and legally reduced. - [Freelancer Tax Deductions 2026](https://www.vortenza.com/guides/freelancer-tax-deductions-2026): Complete 1099 deduction guide for freelancers. - [Federal Income Tax Guide for Freelancers](https://www.vortenza.com/guides/federal-income-tax-freelancers-2026): Federal bracket guide for 1099 workers. - [How to Calculate Mortgage Payment 2026](https://www.vortenza.com/guides/how-to-calculate-mortgage-payment-2026): Amortization formula explained. - [Compound Interest Explained](https://www.vortenza.com/guides/compound-interest-explained): How compound interest works with real examples. - [Debt Snowball vs Avalanche 2026](https://www.vortenza.com/guides/debt-snowball-vs-avalanche-2026): Real math comparison of both debt payoff methods. - [Email Deliverability Guide 2026](https://www.vortenza.com/guides/email-deliverability-guide-2026): Complete guide to email deliverability and inbox placement. - [SPF DKIM DMARC Explained](https://www.vortenza.com/guides/spf-dkim-dmarc-explained): What these DNS records do and why they matter. - [How to Set Up DMARC Record](https://www.vortenza.com/guides/how-to-set-up-dmarc-record): Step-by-step DMARC setup guide. - [Cold Email Deliverability Guide 2026](https://www.vortenza.com/guides/cold-email-deliverability-guide-2026): How to get cold emails into the inbox. - [SPF Setup for Google Workspace](https://www.vortenza.com/guides/spf-setup-google-workspace): Step-by-step SPF record setup for Google Workspace. - [DKIM Setup for Microsoft 365](https://www.vortenza.com/guides/dkim-setup-microsoft-365): Step-by-step DKIM setup for Microsoft 365. - [AI Chatbot Cost 2026](https://www.vortenza.com/guides/ai-chatbot-cost-2026): What AI chatbots actually cost to build and run. - [AI Agent Cost 2026](https://www.vortenza.com/guides/ai-agent-cost-2026): Real cost breakdown for running AI agents. - [Cost Per Token Explained 2026](https://www.vortenza.com/guides/cost-per-token-explained-2026): What cost per token means and how to calculate it.