How QuickFnd Tools Are Built
What standards, formulas, and sources underlie the tools on this site. We believe a free online tool is only as valuable as the assumptions behind it — so here they are, in one place.
Design principles
- Client-side first. Every tool that doesn't structurally require a server — passwords, hashes, JSON formatting, Base64, regex, colour conversion, image compression, PDF merging — runs entirely in your browser. Your input never leaves your device.
- Standard formulas, openly cited. Calculators use the canonical formula for their domain (reducing-balance EMI, Mifflin-St Jeor BMR, ISO 31-11 statistics, etc.). Where multiple standards exist (BMI cut-offs for South Asians vs WHO), we state which we are using.
- No dark patterns. No forced signups, no hidden paywalls on core functionality, no rate limits that only appear after you've invested time.
- Accessible on any device. Every tool is tested on Chrome, Safari, Firefox, and Edge across desktop and mobile.
Developer tools
Hashes and encodings
SHA-256, SHA-1, and MD5 hashes are computed with the native SubtleCrypto.digest API built into every modern browser. Base64 follows RFC 4648 and handles Unicode input correctly via TextEncoder. URL encoding follows RFC 3986.
Regex testing
The regex tester uses the browser's native JavaScript regex engine (PCRE-compatible for most common cases). We display capture groups, lookahead/lookbehind behaviour, and an execution timeline so you can see exactly how your pattern matches.
JSON, YAML, CSV
JSON uses strict parsing (JSON.parse with position-annotated error reporting). CSV handles quoted fields, embedded newlines, and UTF-8 BOM correctly per RFC 4180.
Financial calculators
Our EMI and loan calculators use the standard reducing-balance formula. For a loan of P at monthly rate r over n months, the monthly payment is P · r · (1+r)^n / ((1+r)^n − 1). Full amortisation schedules are generated on the client.
Compound interest supports daily, monthly, quarterly, and annual compounding with optional periodic contributions. SIP calculations assume end-of-month contributions with monthly compounding, matching how Indian mutual fund NAVs are declared.
Tax calculators use the slab logic from the current financial year's tax law, including applicable cess where relevant. We update them once per financial year (April in India, January for US-country calculators). Tax output is informational — for actual filing, consult a qualified professional.
Health calculators
BMI uses the classic kg/m² formula with both the WHO general cut-offs (normal 18.5-24.9) and the South-Asian adjusted cut-offs (normal 18.0-22.9, per the Indian Ministry of Health's 2009 guidelines, which better reflect cardiovascular risk at lower BMI in South Asian populations). We show both.
Calorie and TDEE calculations use Mifflin-St Jeor for basal metabolic rate, with activity multipliers from 1.2 (sedentary) to 1.9 (very active). BMR formulas are informational only — individual needs vary and should be confirmed with a healthcare provider for medical decisions.
AI tools
AI tools (Email Writer, Paraphraser, Cover Letter Writer, etc.) send a single prompt to OpenAI's API with a purpose-built system instruction per tool. We do not store the prompts you submit or the outputs you receive beyond the request lifetime. Each tool is limited to 5 free generations per hour per IP to prevent abuse; a logged-in Pro account raises that limit.
Data we store, data we don't
For client-side tools, QuickFnd stores nothing about your inputs. For AI tools, we send the prompt to OpenAI for generation and return the response; we do not persist the prompt or response on our servers.
If you create an optional account, we store your email, a hashed password, and the tools you've bookmarked. See our Privacy Policy for the complete list.
Accuracy and limitations
We aim for technically-correct, standards-compliant output, but the tools on this site are not a substitute for professional advice. Financial calculators do not account for every fee, regulatory change, or individual circumstance. Health calculators are informational, not diagnostic. Tax calculators reflect the rules as of the last financial-year review. For legally or medically binding decisions, consult a qualified professional.
Spotted an error in a formula, a constant, or a standard we cite? Please contact us — we review methodology feedback within two business days.