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Live2026Web

Free Converter Tools — 71 In-Browser Utilities

71 privacy-first converter tools that run entirely in the browser — files never touch a server.

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Period

2026

My role

Design, Architecture & Engineering (solo)

The Problem

Why this needed to exist.

Popular file-converter sites upload users' documents and photos to third-party servers, wrap the result in ads and paywalls, and cap file sizes to push subscriptions. For most conversions — images, PDFs, data formats, units — that server round-trip is pure overhead: modern browsers can do the work locally, instantly, and privately.

The Approach

How I solved it.

Built a suite of single-purpose tools where every conversion runs client-side — Canvas re-encoding for images, pdf-lib and PDF.js for PDF surgery, streaming parsers for CSV/JSON/YAML/XML, WebCrypto for hashing. A single typed registry drives all 71 routes, category hubs, per-page metadata, JSON-LD and the sitemap, making the suite a programmatic-SEO surface where each tool chunk lazy-loads only its own engine. The one tool needing live data (currency) reads daily ECB rates through a cached API route — no keys, no Redis.

Personas

Who I designed for.

Each persona shaped a specific surface of the product. Goals and pain points were validated through interviews and shadowing.

OP

Nadia

Office Professional

Goals

  • Merge scanned PDFs and convert photos for reports
  • Get results instantly, without creating accounts
  • Keep contracts and payroll files confidential

Pain Points

  • Converter sites upload sensitive documents to unknown servers
  • Watermarks and daily limits behind paywalls
  • Slow upload/download round-trips for large files
DV

Rafi

Software Developer

Goals

  • Quick Base64/JWT/timestamp/hash conversions mid-task
  • Convert API data between JSON, CSV and YAML
  • Trust that pasted tokens and payloads stay local

Pain Points

  • Ad-heavy tool sites with tiny input boxes
  • No confidence about where pasted secrets end up
  • Each utility lives on a different site with different UX

Use Cases

Key user flows.

The most critical scenarios the product is designed to make effortless.

01

Office Professional

Batch-convert images and download as ZIP

  1. 1Drop a folder of PNG screenshots on the PNG→JPG tool
  2. 2Adjust the quality slider; see per-file size deltas
  3. 3Convert all files locally in one click
  4. 4Download individually or grab everything as a ZIP
02

Developer

Debug a JWT without leaking it

  1. 1Paste the token into the JWT decoder
  2. 2Read the decoded header and payload as formatted JSON
  3. 3Check the expiry badge and human-readable iat/exp claims
  4. 4Close the tab — nothing ever left the browser
03

Office Professional

Split a contract PDF into pages

  1. 1Drop the PDF; page count is read locally
  2. 2Enter a range like 2,5-8 or choose burst mode
  3. 3Extract the pages with pdf-lib in-browser
  4. 4Download the new PDF or a ZIP of per-page files

UX Process

How I got from problem to product.

The end-to-end design process — from research to ship.

  1. 01

    One Shell, Many Tools

    Designed a single converter shell — dropzone, options, results, privacy badge — so all 71 tools feel identical and each new tool is mostly a convert() function.

  2. 02

    Registry-Driven Pages

    Every tool is one typed registry entry that generates its route, metadata, FAQ, structured data and sitemap line — content and code can't drift apart.

  3. 03

    Performance Budget

    Tool engines are lazy-loaded per family, so a text tool never ships PDF.js. Static pages keep Core Web Vitals green — the SEO moat for programmatic pages.

Roadmap

What shipped — and what's next.

Phased rollout, with each phase validating learnings from the last.

  1. Phase 1 — Core suite

    Shipped

    Q3 2026

    • 71 tools: image, PDF, data, dev/text, archive, units, dates, currency
    • Shared converter shell + batch ZIP downloads
    • SSG pages with JSON-LD, FAQs and category hubs

  2. Phase 2 — Heavier codecs

    Planned

    Planned

    • ffmpeg.wasm audio conversion (MP3/WAV/OGG/FLAC)
    • HEIC → JPG via WASM decoder
    • AVIF/WebP encoding via jSquash codecs

  3. Phase 3 — Server-side fallback

    Planned

    Planned

    • Queue-based worker for large video and office docs
    • DOCX/PPTX → PDF via headless LibreOffice
    • TTL-based temp storage with signed downloads

Tech Stack

Built with.

Next.jsReactTypeScriptTailwind CSSPDF.jsCanvas API

Engineering Challenges

Hard problems worth solving.

  • Per-family code splitting so 71 tools don't bloat one route bundle
  • PDF.js worker wiring under Turbopack with import.meta.url assets
  • Calendar-accurate date math (leap years, month clamping) without a date library
  • Free, keyless currency data with a cached fallback provider chain

Outcomes

The numbers that matter.

71

Single-purpose tools, each on its own indexable page

0

Files uploaded — every conversion runs on-device

<1s

Typical conversion time, no network round-trip

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