Reverse DNS Lookup resolves IPv4 and IPv6 addresses into their associated hostnames via PTR records. Pass any IP address to check if reverse records exist and receive all matching hostnames.

Reverse Geocode converts latitude and longitude coordinates into US and Canada location details. Pass geographic coordinates to retrieve the corresponding city, state, postal code, and country code.

Reverse Text transforms text by reversing characters, words, or lines with multiple reversal modes for different use cases.

Ring Size Converter translates international ring sizes or millimeter diameters into US and UK standards, inside diameter, and circumference. Paid plans add equivalent sizes for Europe, Japan, Switzerland, and Australia.

Rock Paper Scissors API simulates the classic hand game with detailed outcome analysis, statistics, and support for multiple rounds.

Roman Numeral Converter is a bidirectional tool for converting between Arabic numbers (1-3999) and Roman numerals. It provides detailed breakdowns of the conversion process.

Roman Numeral Math computes addition, subtraction, multiplication, and division between two Roman numerals. It returns the calculated result and complete equation in both Roman numeral and standard integer formats.

Routing Number Lookup is a bank routing number lookup API that verifies US ABA routing numbers to confirm bank names, states, and checksum validity. It identifies the routing type and Federal Reserve district, while paid plans add full street addresses, branch details, and replacement numbers.

RSS to JSON converts any RSS feed URL into structured JSON in real time. Each response returns the source domain, article counts, headlines, publication dates, summaries, and direct article links.

Sales Tax Lookup is a US sales tax API that finds current sales tax rates for any US ZIP code or two-letter state abbreviation. It returns the jurisdiction state code and the estimated combined tax rate.

Sales Tax Calculator is a US sales tax API that computes the exact sales tax amount and combined rate for purchases in any US state or ZIP code. Paid plans add breakdowns by state, county, city, and special district rates.

Sanctions Screening checks a person or company name against the US Treasury OFAC Specially Designated Nationals (SDN) list. It returns scored matches with aliases, dates of birth, addresses and sanctions programs so you can decide whether to block or review.

I-Bond Rates provides current and historical interest rates for US Series I Savings Bonds. I-Bonds are inflation-protected savings bonds with a composite rate made up of a fixed rate plus an inflation rate that adjusts every 6 months.

Scrabble Word Scorer calculates the official Scrabble score for any word across five languages. It provides the total base points, letter count, and point values for each individual letter.

SEC Filings returns the recent EDGAR filing history for a US public company by ticker - 10-K annual reports, 10-Q quarterlies, 8-K current reports, Form 4 insider filings, S-1 registrations and more - each with its filing date, form type and a direct link to the document, plus derived filing-activity analytics calculated for you.

Sentiment Analysis evaluates the emotional tone of any text string. It returns an AFINN valence score, a comparative word-normalized score, and a five-tier sentiment label from very negative to very positive.

SEO Data Scraper parses any public URL to collect title tags, meta descriptions, robots directives, and Open Graph or Twitter card previews. Paid plans add canonical URLs to verify indexing rules.

SEO Quick Validator inspects live web pages for on-page SEO errors and tag issues. Pass any URL to inspect title lengths, meta descriptions, H1 headings, viewport and canonical tags, image alt text, and unverified external links.

Shoe Size Converter translates footwear measurements across regional standards, including US, UK, Australian, Mexican, and Korean sizing systems. Provide a size, source region, and gender category to get equivalent sizes, with paid plans adding European, Japanese, and centimeter measurements.

Short Code Generator creates custom alphanumeric short codes for vouchers, referral tokens, and redirect slugs. Specify a length, batch count, and character set like numeric, hex, or Base58 to receive an array of random strings.