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Folia research-paper.pdf

On-Device Document Processing for Privacy-Preserving PDF Workflows

J. Park · M. Olsen · K. Reza

Correspondence: privacy@foliadocs.com

Abstract

We present a document-processing pipeline that performs conversion, editing, optimization and redaction entirely on the user's machine. No page content, metadata, or derived artifact is transmitted to a remote service. Each operation re-reads its own output to verify integrity before the result is shown to the user.

1. Introduction

Portable Document Format remains the default container for legal, academic and financial records. Yet most tooling routes files through cloud infrastructure, expanding the trust boundary far beyond the author's intent.

Our approach keeps every byte in process memory. We show that local execution matches server-side throughput for documents up to one hundred megabytes while eliminating network exposure entirely.

Verified result

Redaction

Re-extracted text — 0 remain.

Encryption

Reopened — AES-256 (V5/R6).

PDF → Word

Layout-faithful — fonts kept.

0 network calls

Nothing leaves your device

Processed in-memory, on-device

Built for ResearchersLegal & financeMedical & govStudentsMultilingual prosGeneral useHeavy useSensitive documents

Why Folia

Three unhappy options. One calm answer.

Everything people reach for today asks them to give something up — money, privacy, or capability.

vs Adobe Acrobat

Heavy, expensive, subscription-locked and cluttered.

Calm and focused, with a generous free tier and a one-time Lifetime option.

vs free online tools

They upload your file to a stranger’s server.

100% of the work runs on your machine — the file never leaves the device.

vs built-in viewers

View-only. They can’t actually change anything.

Edits, converts, redacts, signs, OCRs and more — for real.

The five pillars

What we build everything around.

Private by design

Nothing is uploaded. Enforced by the app’s architecture, not just a promise.

Genuinely complete

24 headline tools plus Document Tools, Power Tools and an AI platform.

Honest & verified

Operations re-read their own output to prove they actually worked.

Truly multilingual

Fully EN + KO interface; the text editor handles 40+ scripts.

Calm & fast

Pixel-crafted, token-driven, keyboard-first, light & dark.

Genuinely complete

Everything you do to a PDF, in five categories.

24 headline tools that replace a stack of separate apps and sketchy upload sites.

Organize

Arrange, split & combine pages

Merge PDFs

Split

Extract pages

Delete pages

Insert from file

Reorder

Rotate

Duplicate page

Convert

Move between PDF & other formats

PDF → Word

PDF → Excel

PDF → PowerPoint

PDF → Image

Images → PDF

Office → PDF

Edit

Change content & add markups

Edit existing text

Add text FREE

Whiteout

Rich text

Highlight FREE

Underline / Strike

Pen / Draw

Text notes FREE

Redact

Watermark

Page numbers

Forms

Sign

Optimize

Shrink & read your documents

Compress

OCR — 90+ languages

Security

Protect, sign & lock down files

Protect — AES-256

Digital signature (PAdES)

Unlock

Flatten

Sanitize

Bates numbering

Search & redact

Plus Document Tools, Power Tools & AI

Sanitize, Bates, PDF/A, Compare, Measure, Batch and the on-device AI platform.

See the full catalog

Privacy & verification

Nothing uploaded. And it proves its work.

Folia is a hardened desktop app — document bytes are processed in-memory, on-device. A fresh install makes essentially zero network calls until you opt in. Destructive and security operations re-read their own output to prove they actually worked.

Local-first by architecture — a sandboxed renderer with no hidden network calls.

Network-off-by-default — a fresh install is fully offline until you opt in.

Clearly-flagged exceptions — only consented plugins and one-time downloads ever reach out.

Real cryptography — verified AES-256 and PAdES handled in an isolated process.

Redaction

re-extracted text · 0 remain

PASS

Encryption

reopened · AES-256 (V5/R6, 256-bit)

PASS

Sanitize

metadata re-counted · clean

PASS

Folia never fakes success — “Done” is always evidence.

Edit existing text

beforeTeh resluts were significant.

afterThe results were significant.

Same font, color and size — even in 40+ scripts:

English中文हिन्दीEspañolFrançaisالعربيةবাংলাPortuguêsРусский日本語한국어DeutschTiếng ViệtไทยעבריתΕλληνικάदेवनागरीខ្មែរLatin

Edit · Multilingual

Edit a finished PDF — in its own font, in any language.

Click any line of real text and retype it. Folia matches the document's own embedded font, samples the ink and background color, and width-fits the replacement so nothing shifts. The text editor handles Korean, Arabic, Hebrew, Thai, Devanagari, CJK and Khmer — with right-to-left and complex-script shaping that other tools turn into boxes.

40+

scripts shaped correctly

~70

curated open-source fonts

EN · KO

100% bilingual UI

AI platformBETA

AI that reads your documents without sending them anywhere.

Every AI feature runs through one gateway. Folia Local AI runs entirely on your device — private and free. The model downloads once and then works with no network at all, so the text of your document never leaves your machine. A per-document "Local only" lock is there as well, for files you want kept strictly on-device no matter what.

Chat with citationsSummaries & study guidesRewrite & proofreadRead-aloud

AI AssistantLocal engine

Summarize the methodology and cite pages.

The study used a randomized controlled design (n=240) over 12 weeks [p.4], with double-blind allocation [p.5].

Study guideKey termsMind-map

Convert with real fidelity

PDF to Word that still looks like your PDF.

Layout-faithful, not reflowed — same fonts, same colors, real tables, exact positions. Locally.

Source PDF

Editable .docx

PDF → WordPDF → ExcelPDF → PowerPointPDF → ImageImages → PDF

Sign · Fill · Send

Sign it yourself — or collect signatures and watch them land.

Fill any form and sign on-device with a drawn or uploaded signature, then apply a tamper-evident PAdES digital signature. Need others to sign? An optional send-for-signature service (coming soon) will let you follow every step — Sent → Opened → Signed — in real time, with documents end-to-end encrypted and removed the moment everyone has signed.

Drawn or uploaded signaturePAdES digital signatureFillable formsReal-time status

Signature request 2 signers

Service-agreement-v3.pdf

Sent today · 14:02

You signed

On-device · PAdES applied

Done

Opened by J. Park

j.park@firm.com · 2m ago

Opened

Awaiting M. Olsen

m.olsen@firm.com

Pending

End-to-end encrypted · removed after signing

Power tools

For the professionals who push hardest.

Compare documents

Word-level diff between two PDFs, page by page — additions in green, deletions struck in red, with whole-document totals.

Measure

Click for distance or area on the rendered page, and calibrate a real-world scale from a segment of known length.

Batch processing

Apply a chain of tools to many PDFs at once — resilient per file, with a review step and save-all into a folder.

By the numbers

What Folia actually does.

Your documents are processed on your own computer — every tool, every time.

files uploaded, ever

headline tools

90+

OCR languages

40+

scripts shaped

Pricing

Free to start. Buy once, keep forever.

A genuinely useful free tier, low subscription prices, and a one-time Lifetime license — no Acrobat-style subscription lock-in.

Free

View, annotate & note — forever, no account.

No card needed

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Student

Organize + everything in Free, verified by school email.

$1.00/mo

billed annually

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Folia fits the way you already work.

It slots into your file manager, your Office files and even your phone — and your documents stay on your device throughout.

Right-click to open

A File Explorer and Finder entry opens any PDF straight into Folia — no upload dialog, no browser tab.

Your default PDF reader

Set Folia as the system viewer and every PDF you double-click opens in a calm, fast, private workspace.

Office & images in

Drop Word, PowerPoint and images onto Folia to rebuild them as a single clean PDF.

Scan from your phone

Pair over your own local network and captured pages arrive on the desktop — never routed through anyone’s cloud.

Command palette

Every tool is one keystroke away. Folia is keyboard-first, so power users barely touch the mouse.

Settings sync, not files

Your accent, shortcuts and preferences follow you between machines. Your documents never do.

Windows

Available now

NSIS installer. No file-size limit — work with documents of any size. No account needed for the free tier.

Download for Windows

macOS

Coming soon

A universal build for Apple Silicon & Intel is in active development — same tools, same privacy. Tell us where to send the launch news.

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FAQ

Questions, answered honestly.

From privacy to pricing — the answers to everything people ask, gathered in one place.

Browse the full FAQ

Your documents never leave your device.

Start free today — no card, no account, nothing uploaded.

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