# ApexCalc vs InvoiceNumberGenerator compared

> ApexCalc vs InvoiceNumberGenerator: pricing, platforms, launches, upvotes and founders side by side on ProductsFarm, with notes on which to pick.

Canonical: https://productsfarm.com/compare/apexcalc-vs-invoicenumbergenerator
Last updated: 2026-11-10

|  | [ApexCalc](https://productsfarm.com/product/apexcalc) | [InvoiceNumberGenerator](https://productsfarm.com/product/invoicenumbergenerator) |
| --- | --- | --- |
| What it is | Free online calculators for medicine, engineering, finance and science | Tracks unpaid invoices and client balances in your browser — free, no sign-up. |
| Pricing | Free | Freemium |
| Platforms | Web | Web |
| Categories | Productivity, Education | Finance, Productivity |
| Made for | students, professionals, finance teams | freelancers, small business owners |
| Built with | [Tailwind CSS](https://productsfarm.com/tech-stack/tailwind-css) | [Cloudflare](https://productsfarm.com/tech-stack/cloudflare) |
| Upvotes | 14 | 0 |
| Website | [apexcalc.net](https://apexcalc.net/) | [invoicenumbergenerator.com](https://invoicenumbergenerator.com/invoice-tracker) |

## About ApexCalc

ApexCalc is a free web platform that gathers calculators across more than 50 disciplines, including medicine, engineering, finance, science, law, and sports and fitness. The site lists over 11,600 tools, which can be searched or browsed by category and opened in the browser without signing up or installing anything.

Each calculator opens on its own page. The site says its tools include formula logic, sourced citations and links to related tools. It also lists regional finance, tax, mortgage and legal tools for 150 countries, alongside everyday calculators such as BMI and mortgage tools.

The platform is aimed at students, professionals and anyone who needs a quick answer in a specific field. The site states that every calculator is free with no account required. It also describes paid tiers for saved bookmarks, PDF export and API access, but these are marked as coming soon and are not yet available.

## About InvoiceNumberGenerator

Invoice Tracker is a web app from Invoice Number Generator for keeping track of invoices that are still waiting to be paid. Entries are saved locally in your browser, and each one shows its due date, amount and client. The tracker sorts unpaid invoices into aging buckets, so you can see what is current, what is 1 to 30 days overdue, 31 to 60 days overdue, and more than 60 days overdue. Totals are kept separately for each currency, and paid invoices leave the buckets.

You can add invoices by hand, or import them from a CSV file using a column template. The import preview shows errors with their file line numbers so you can fix them before saving. Invoices created with the site's invoice generator can be copied into the tracker after you download or send them. The copy does not change when you later edit the original invoice. Raw CSV and JSON backups are free to export, which matters because local data is removed if browser data is cleared.

The tracker suits freelancers and small businesses that want a simple view of who owes them money without signing up. Starter and Pro plans add cloud save and sync, formatted Excel and PDF statement reports, and a premium spreadsheet template. Pro also adds automatic payment reminders and recurring invoices for cloud-saved invoices.

## Related

- [ApexCalc](https://productsfarm.com/product/apexcalc)
- [InvoiceNumberGenerator](https://productsfarm.com/product/invoicenumbergenerator)
- [More comparisons](https://productsfarm.com/compare)