Data Sources & Update Policy
Every dataset powering our calculators — its authoritative source, update frequency, and last verification date.
How we keep data accurate
FreeToolHub runs a self-enforcing data authority framework. Every calculation dataset is registered with its official source (IRS, SSA, state agencies, primary industry data). At every build, the site re-verifies that the shipped numbers still match independently hard-coded official values — a mismatch fails the build, so stale or wrong data can never reach production unnoticed.
- Sourced: 54 datasets, 101 cited official sources — a dataset without a source cannot ship.
- Cross-checked: official ground-truth values ↔ runtime data files ↔ offline fallback constants must agree (3-way consistency gate).
- Formula-audited: calculation formulas are re-verified against official worked examples with citations (see the formula verification matrix in our public repository).
- Fresh: scheduled updates with staleness detection — datasets past their review window raise alerts automatically.
- Regression-proof: auto-updaters refuse to write older tax-year data over newer data.
This page reflects the data registry as of 2026-10-13. If you spot a discrepancy with an official source, please report it — we treat accuracy reports as highest priority.
| Dataset | Used by | Updates | Last updated | Effective | Official sources |
|---|---|---|---|---|---|
| 1099-NEC/MISC Filing Rules | /1099-nec-misc/ | Annual | 2026-01-01 | 2026 tax year | IRS — Form 1099-NEC InstructionsIRS — Form 1099-MISC Instructions |
| 401(k) Contribution Limits | /401k-vs-roth/ | Annual | 2025-11-13 | 2026 tax year | IRS Newsroom — 401(k) limit increases to $24,500 for 2026 (IR-2025-111)IRS Notice 2025-67 (2026 retirement-plan COLA, PDF)IRS — COLA Increases for Dollar Limitations (§415(c) 2026 = $72,000) |
| Advertising ROI & ROAS Formulas | /roi-calculator/ | Manual review | 2026-06-01 | Standard formulas — no expiration | Google Ads — ROI & ROAS Guide |
| AI Background Removal Model (ONNX) | /ai-bg-remover/ | Manual review | 2026-06-01 | Model v1.7.0 (ONNX WASM, downloaded on first use) | @imgly/background-removal (npm)IMG.LY — Background Removal Docs |
| AI Image Upscaling Algorithm | /ai-image-upscaler/ | Manual review | 2026-06-01 | Browser Canvas API — no expiration | MDN — Canvas imageSmoothingQuality |
| AI Prompt Engineering Templates | /prompt-generator/ | Manual review | 2026-06-01 | 2026 template formats | OpenAI — Prompt Engineering Guide |
| AI Text Generation Models | /ai-email-writer//ai-paraphraser//ai-resume-rewriter/ | Manual review | 2026-06-01 | Powered by GPT models (2026) | OpenAI GPT API |
| Break-Even Analysis Formula & Assumptions | /break-even-calculator/ | Manual review | 2026-06-01 | Standard CVP (Cost-Volume-Profit) model — no expiration | Investopedia — Break-Even AnalysisSBA — Break-Even Analysis |
| Browser Image Processing APIs | /image-resize//img-base64//webp-conv//svg-convert/ | Manual review | 2026-06-01 | Browser-native APIs — no expiration | MDN — Canvas APIMDN — File API |
| Canvas API — Blur Filter | /bg-blur/ | Manual review | 2026-06-01 | Browser Canvas API — no expiration | MDN — CanvasRenderingContext2D.filter |
| Color Space Conversion Standards | /color-picker/ | Manual review | 2026-06-01 | W3C CSS Color Level 4 — no expiration | W3C — CSS Color Module Level 4ICC — Color Management |
| Copyright & Public Domain Rules | /copyright-pd/ | Annual | 2026-01-01 | U.S. Copyright Law (Title 17) — 2026 | U.S. Copyright Office — Duration of CopyrightCornell University — Copyright Term and the Public Domain |
| CSS Gradients Specification | /css-gradient/ | Manual review | 2026-06-01 | W3C CSS Images Level 3 — no expiration | MDN — CSS gradientW3C — CSS Images Module Level 3 |
| Currency Exchange Rates | /currency/ | Daily● live | 2026-10-13 | Live rates as of 2026-10-13 | Frankfurter API (ECB reference rates) |
| Date & Time Calculation Standards | /date-diff//countdown/ | Annual | 2026-01-01 | Gregorian calendar — no expiration | ISO 8601 — Date and Time FormatIANA Time Zone Database |
| English Grammar Rules Database | /grammar-checker/ | Manual review | 2026-06-01 | Rule-based — no expiration | Common English Errors — rule base |
| EU VAT Rates — 27 Member States | /vat-calculator/ | Annual | 2026-01-01 | 2026 VAT rates (verified Jan 2026) | EU Council — VAT RatesPwC — EU VAT Rate Table |
| Federal Income Tax Brackets | /w2-vs-1099//capital-gains//self-employment-tax//crypto-profit//freelancer-tax//1099k-tax//401k-vs-roth/ | Annual | 2026-09-03 | 2026 tax year | IRS Rev. Proc. — Annual Inflation AdjustmentsIRS.gov — Tax Brackets & Rates |
| Freelance Industry Rate References | /pricing-calculator/ | Annual | 2026-01-01 | 2026 reference rates | Upwork — Freelancer Rate ReportGlassdoor — Salary Data |
| GDPR Regulation Text & Articles | /gdpr-request/ | Manual review | 2026-06-01 | GDPR (Regulation EU 2016/679) — effective since May 25, 2018 | EUR-Lex — GDPR Full Text |
| Guerrilla Mail Temporary Email API | /temporary-email/ | Real-time● live | 2026-06-18 | Live API — real-time | Guerrilla Mail — Free Temporary Email API |
| HS Code Duty Rates (US, EU, UK) | /tariff-calculator/ | Annual | 2026-01-01 | 2026 tariff rates (approximate averages) | US HTS — Harmonized Tariff ScheduleEU TARIC — Integrated TariffUK Trade Tariff |
| HSA / FSA Contribution Limits | /hsa-fsa-calculator/ | Annual | 2026-08-28 | 2026 tax year | IRS Pub 969 — Health Savings AccountsIRS Rev. Proc. 2025-19 — 2026 HSA/HDHP amountsIRS Rev. Proc. 2025-32 — 2026 health FSA limit & carryover |
| HTML Email Compatibility Standards | /email-template/ | Annual | 2026-01-01 | 2026 email client compatibility | Can I Email — Compatibility TableMailchimp — Email CSS Guide |
| Inflation Rate (CPI-U) | /compound/ | Monthly | 2026-08-01 | 3.4% (BLS CPI-U trailing 12mo, 2026-08-01) | BLS — Consumer Price Index |
| Invoice Generator Processing | /invoice-generator/ | Manual review | 2026-06-01 | N/A — 100% client-side, no external data | All data stays in your browser — no server, no API, no cloud |
| IRS Life Expectancy Tables & RMD Rules | /rmd-calculator/ | Annual | 2026-08-17 | 2022 R2 Uniform Lifetime Table + Joint Life and Last Survivor Expectancy Table | IRS — Pub 590-B: Distributions from Individual Retirement Arrangements |
| LLC Formation & Annual Fees by State | /llc-cost/ | Manual review | 2026-08-17 | 2026 fees (verified Aug 2026) | State Secretary of State websitesLLC University — State-by-State LLC Costs |
| LLM API Pricing & Token Ratios | /token-calculator/ | Manual review | 2026-08-17 | Pricing as of August 2026 (subject to change) | OpenAI PricingAnthropic PricingGoogle AI Studio PricingDeepSeek PricingMeta Llama — Together AI Pricing |
| LLM Tokenizer Character-to-Token Ratios | /token-calculator/ | Manual review | 2026-06-01 | Approximate ratios (2026 models) | OpenAI Tokenizer (tiktoken)Anthropic Token CountingGoogle Gemini Tokenization |
| Long-Term Capital Gains Tax Brackets | /capital-gains//crypto-profit/ | Annual | 2026-09-03 | 2026 tax year | IRS Pub 550 — Investment Income & Expenses |
| Mortgage Interest Rates & PMI | /mortgage-calculator/ | Manual review | 2026-10-08 | 7.40% default (Freddie Mac PMMS 30yr fixed, 2026-10-08) | Freddie Mac — Primary Mortgage Market Survey |
| Net Investment Income Tax Thresholds | /capital-gains//crypto-profit/ | Manual review | 2025-01-01 | Not inflation-indexed ($200K/$250K since 2013) | IRC §1411 — Net Investment Income Tax |
| Password Strength Analysis Methods | /password-strength/ | Manual review | 2026-06-01 | Analysis methods — no expiration | NIST SP 800-63B — Digital Identity GuidelinesHave I Been Pwned — Breach Database |
| Payment Processor Fee Rates | /payment-compare/ | Manual review | 2025-06-01 | As of 2025 (fees subject to change) | Stripe PricingPayPal Merchant FeesSquare PricingWise Business Pricing |
| Pedigree Registry Certificate Formats | /pedigree-lookup/ | Manual review | 2026-06-01 | 2026 registry formats | AKC — American Kennel ClubThe Kennel Club (UK)TICA — The International Cat AssociationCFA — Cat Fanciers' Association |
| QR Code Specification (ISO/IEC 18004) | /qr-logo-gen/ | Manual review | 2026-06-01 | QR Code standard — no expiration | ISO/IEC 18004 — QR Code Spec |
| Reseller Platform Fee Rates | /reseller-profit/ | Manual review | 2025-06-01 | 2026 platform fees | eBay Seller FeesPoshmark FeesMercari FeesEtsy Seller Fees |
| Schema.org Structured Data Specification | /ai-schema-generator/ | Annual | 2026-06-01 | Schema.org v26.0 (2026 release) | Schema.org — Full Type HierarchyGoogle Search Central — Structured DataGoogle Rich Results Test |
| Shopify Plan Pricing & Payment Rates | /dropship-profit/ | Manual review | 2025-06-01 | 2026 Shopify fees | Shopify Pricing PlansShopify Payments Rates |
| Social Media Image Dimensions 2026 | /social-resizer/ | Monthly | 2026-06-01 | 2026 platform dimensions | Sprout Social — Social Media Image Sizes |
| Social Security Wage Base | /self-employment-tax//freelancer-tax//1099k-tax/ | Annual | 2026-07-26 | 2026 tax year | SSA — Social Security Wage Base |
| Standard Deductions | /w2-vs-1099//self-employment-tax//freelancer-tax//1099k-tax//capital-gains//crypto-profit//dropship-profit/ | Annual | 2026-09-03 | 2026 tax year | IRS Rev. Proc. — Annual Inflation Adjustments |
| State & Local Sales Tax Rates | /sales-tax/ | Annual | 2026-08-17 | 2026 rates (avgLocal/maxLocal are pure local rates, NOT combined) | Sales Tax Institute — State RatesAvalara — State & Local Rates |
| State Income Tax Rates (Progressive Brackets) | /w2-vs-1099//self-employment-tax//crypto-profit//freelancer-tax//1099k-tax//dropship-profit//reseller-profit//payroll-tax-calculator//quarterly-tax-reminder/ | Annual | 2026-06-18 | 2025-2026 tax year (progressive brackets where applicable) | Respective state Department of Revenue websitesTax Foundation — State Income Tax Rates |
| State Non-Compete Agreement Laws (50 States + DC) | /non-compete-checker/ | Annual | 2026-06-01 | 2026 state non-compete laws (verified Jan-Jun 2026) | NCSL — Non-Compete AgreementsFair Competition Law — 50-State SurveyEconomic Policy Institute — Non-Compete Reform |
| State Tax Reciprocity Agreements | /payroll-tax-calculator//multi-state-tax/ | Annual | 2026-07-11 | 2026 reciprocity agreements | Respective state Department of Revenue websites — reciprocity agreements |
| Subscription Cancellation Templates | /cancel-subscription/ | Manual review | 2026-06-01 | 2026 template formats | FTC — Cooling-Off Rule |
| TextRank Summarization Algorithm | /pdf-text-extract/ | Manual review | 2026-06-01 | Algorithm-based — no expiration | TextRank: Bringing Order into Texts (Mihalcea & Tarau, 2004) |
| Time Zone Database (IANA) | /timezone-converter/ | Monthly | 2026-06-01 | IANA tzdata 2026a | IANA Time Zone Database |
| Tip Calculator — Sales Tax & Tipping Norms | /tip-calculator/ | Annual | 2026-01-01 | 2026 state sales tax rates & standard tipping norms | Sales Tax Institute — State RatesETiquette Scholar — Tipping Guide |
| US Economic Nexus Thresholds by State | /nexus-checker/ | Annual | 2026-01-01 | 2026 thresholds (verified Jan 2026) | Avalara — Economic Nexus State GuideWayfair ruling — South Dakota v. Wayfair (2018)State revenue department websites |
| Visa Bulletin — Priority Date Cutoffs | /green-card-priority-date/ | Monthly | 2026-06-01 | June 2026 Visa Bulletin (DOS published May 2026) | U.S. Dept. of State — Visa BulletinUSCIS — When to File AOS |
| W-4 Withholding Tables & Brackets | /w4-calculator/ | Annual | 2026-01-01 | 2026 tax year | IRS — Form W-4IRS — Withholding Tables (Pub 15-T) |
Data is for estimation and informational purposes only and does not constitute tax, legal, or financial advice. Verify critical figures against the linked official sources before acting on them.