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Declan
Declan

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Building File Utilities That Run 100% in the Browser

I recently built filetools, a suite of file utilities that run entirely in the browser. No server backend, no file uploads, no data collection.

The Problem

Existing tools for CSV extraction, PDF manipulation, and table conversion often require uploading files or creating accounts. That creates friction and privacy concerns. But these tasks are fundamentally simple: extracting text from a PDF or parsing a CSV can happen entirely in JavaScript.

The Solution

filetools is a collection of single-purpose utilities:

PDF Tools:

  • Merge, split, rotate PDFs
  • Extract tables from PDFs to CSV
  • Convert bank statements to CSV

Data Tools:

  • Extract tables from HTML to CSV or JSON
  • Convert between XLSX, JSON, YAML, and CSV
  • Remove duplicate lines, sort CSV files, merge/compare data files

Each tool is its own page, targeting one specific task without bloat.

Architecture

Why static hosting? Keeps infrastructure simple and costs near zero. Files are built once, served from GitHub Pages.

Why client-side only? User files never leave their machine. Processing is fast (no network round-trip). Privacy is the default.

Tech stack: vanilla JavaScript using npm libraries (pdfjs-dist, exceljs, js-yaml, pdf-lib) - no framework, no server. Each page is roughly 5-15KB gzipped.

Design: Started with demand mining, looking at actual Google search queries and autocomplete suggestions to pick which tools to build first.

What's Next

Live site: https://usefiletools.com/?utm_source=dev.to&utm_medium=article&utm_campaign=filetools-launch

I'm building more tools based on real search demand. If there's a file utility you've always wished existed, especially for data professionals, I'd love to hear about it.

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