Exact fraction arithmetic: Parse signed integer fractions with BigInt, apply the selected operation, normalize the denominator sign and reduce by the greatest common divisor.

Money & borrowing

Extra loan payment savings

Compare payoff time and interest with and without an additional monthly loan payment.

Developer & data

Extract a column from CSV

Extract one CSV column as a JSON array, with an optional spreadsheet-safe one-column CSV download.

Developer & data

Extract email-like addresses and web URLs

Extract email-like addresses and web URLs: Find conservative email-like ASCII tokens or HTTP(S) URL tokens, remove duplicates and return the first occurrence order.

Images & PDFs

Extract PDF pages

Extract PDF pages: Copy a 1-based inclusive page range to a new PDF; start and end are required.

Math & statistics

Factorial

Factorial: n! = 1 × 2 × … × n; 0! = 1

Home & construction

Fence panels and posts

Plan panel and post counts for an open fence run or a closed loop, plus a basic materials budget.

Developer & data

Filter a JSON object array

Filter a JSON object array: Parse the match as a JSON scalar, then keep objects whose own named property is exactly equal in both type and value.

Developer & data

Filter CSV rows by a column

Filter CSV rows by a column: Parse CSV and retain rows whose selected cell equals, contains, or differs from the entered case-sensitive text.

Text & writing

Find and replace

Find and replace: Literal, case-sensitive global replacement. Regular expressions are not executed.

Developer & data

Find and replace within a CSV column

Find and replace within a CSV column: Parse CSV, replace every exact case-sensitive occurrence in the selected column only, and serialize valid CSV.

Developer & data

Find duplicate CSV keys

Find duplicate CSV keys: Build exact composite keys from the selected cells.

Dates & time

Fiscal quarter and date boundaries

Fiscal quarter and date boundaries: Offset the calendar month from the fiscal starting month, take the zero-based quarter, then find the first and last calendar dates in that three-month block.

Money & borrowing

Fixed-coupon bond price

Value a fixed-coupon bond by discounting its remaining coupons and maturity payment at an entered yield.

Developer & data

Flatten JSON to pointer entries

Flatten JSON to pointer entries locally in your browser, with clear input requirements, a worked example and an explanation of the result.

Web & design

Fluid font-size CSS clamp generator

Fluid font-size CSS clamp generator with editable inputs, an explained method, a worked example and clearly stated output limits.

Physics & engineering

Fluid pressure from liquid head

Fluid pressure from liquid head using clearly labeled inputs, with the formula, a worked example and practical limits explained.

Unit converters

Force converter

Force converter: result = amount × source factor ÷ destination factor. Factors are relative to N.

Travel & transport

Foreign card and ATM cost

Estimate a foreign purchase or ATM withdrawal cost after conversion, percentage markup and a fixed fee.

Electronics & energy

Four-band resistor color decoder

Four-band resistor color decoder: Decode the first two bands as decimal digits, apply the third-band multiplier and use the fourth band as percentage tolerance.