About TheCalculatorHubs

Who built this site

TheCalculatorHubs is built and maintained by Abishek, a solo developer based in India. The site began in 2024 as a single Aadhaar photo resizer when I noticed how many people were uploading sensitive ID photos to random websites just to compress a JPEG to 50 KB. There was no good reason for that file to leave anyone's device — modern browsers can do every step of the work locally. So I built one that runs entirely in the browser tab, and from there the site grew into the broader collection of more than 25 tools you see today.

I write all the code, all the explanatory content, and all the formulas you see on this site myself. Every calculator on TheCalculatorHubs uses the standard formulas published by the relevant Indian regulatory authorities — RBI for loan EMI, the GST Council for tax slabs, UIDAI for Aadhaar photo specifications, the Income Tax Department for tax calculations. Whenever a regulation changes (new GST rates, new tax slabs in the Union Budget, updated Aadhaar fee schedules), I update the affected pages and note the change date.

If you spot an error in a calculation, a typo in an explanation, or a regulation that has changed and not yet been reflected on the site, please email thecalculatorshub@gmail.com. I read every email and reply within 24 to 48 hours.

How calculations are verified

Every financial calculator on this site implements the formula in plain JavaScript, with the formula visible on the tool's page so you can verify it yourself. For Indian tax and finance calculations, results are cross-checked against the official calculators published by the Income Tax Department of India (incometaxindia.gov.in) and reputable independent sources such as ClearTax, BankBazaar, and Groww. Photo specifications for Aadhaar, PAN, and government exam forms come directly from the relevant authority's published guidelines (UIDAI, NSDL/UTI for PAN, individual exam authorities for state PSCs).

Important disclaimer: The calculators on this site produce estimates intended for personal planning only. They are not a substitute for professional financial, legal, tax, or medical advice. Before making any consequential financial decision (taking a loan, changing your tax regime, starting an SIP, restructuring debt), please consult a qualified Chartered Accountant, financial advisor, or relevant expert. For Aadhaar, PAN, or other government document submissions, always cross-check current specifications on the official government portal — government rules change without prior notice.

Why we built this

Most "free online file converters" upload your documents to their servers, run a conversion script, and email or stream back the result. It works, but every file you process passes through someone else's infrastructure — usually with vague privacy terms and no real way to verify the file was deleted afterwards.

That bothered me. Modern browsers can do almost everything those services do — image compression, PDF merging, format conversion, calculations — without sending a single byte to a server. So I built TheCalculatorHubs to take advantage of that. Every tool here runs as JavaScript in your tab, using libraries like pdf-lib, pdf.js, Mammoth, and the native Canvas API. There's no upload because there's no server that handles files.

What you can do here

TheCalculatorHubs currently offers more than 25 tools across five categories:

• PDF tools — merge, split, compress, rotate, reorder, add page numbers, convert to/from JPG and Word.
• Image tools — compress, resize to a target KB size, convert formats, batch compress to ZIP.
• India utility tools — Aadhaar photo resizer (with strict KB limits), passport photo maker for multiple countries, signature resizer for exam and banking forms.
• Financial calculators — loan EMI, compound interest / SIP, GST, currency conversion, percentage and discount calculations.
• Daily utilities — BMI calculator, age calculator, word counter with reading time.

New tools are added regularly based on user requests and search demand. The ones I prioritize most are the tools with strong everyday utility for Indian users that can be built reliably as static, browser-only utilities — no backend required.

Editorial policy

Every blog post and explanatory section on this site is written by me from scratch. I don't republish AI-generated boilerplate, scrape competitor content, or use ghost-written agency copy. When I cite an interest rate, a tax slab, or a fee schedule, the figure comes from a primary source (RBI, UIDAI, Income Tax India, GST Council notifications) and I link to that source whenever possible. If a published figure changes between updates, the affected page is corrected within seven days of me becoming aware.

How it stays free

TheCalculatorHubs displays advertising served by Google AdSense. Ads keep the site free for everyone and pay the costs of building, hosting, and maintaining new tools. The site does not show pop-ups, intrusive interstitials, or pre-roll ads. Ad placements are clearly marked and never blend with tool functionality. There are no paywalls, no premium tiers, and no signup required to use any tool.

Built with open source

The tools rely on well-established open-source JavaScript libraries:

• pdf-lib — for creating, merging, splitting, and editing PDFs.
• pdf.js — Mozilla's PDF rendering engine, used to extract text and render previews.
• Mammoth.js — for reading .docx files.
• Canvas API — native browser API for image compression and resizing.

All processing happens locally in your browser tab. The libraries run in a sandboxed page and have no network access of their own.

Contact

For questions, bug reports, feature requests, or correction notices, email thecalculatorshub@gmail.com. I reply within 24 to 48 hours during business days. There is no phone number — the site is run as a one-person project, and email is the most reliable way to reach me.

Performance and accessibility

The site is built with vanilla HTML, CSS, and JavaScript — no React, no build step, no framework overhead. Each tool page is under 15 KB of HTML. Heavy libraries are loaded on demand, not on every page. We aim for Lighthouse scores above 95 across performance, accessibility, best practices, and SEO.

Contact

Found a bug, want a new tool, or have a question? See our Contact page.