FirstLocal.studio — LocalPDF
User Guide & Tool Reference
Your files stay
where they belong.
A complete reference for LocalPDF — how browser-based PDF processing works, how to use all six tools, common real-world workflows, and answers to the questions that come up most.
Table of Contents
- 01How LocalPDF works — the privacy model3
- 02Merge PDFs5
- 03Split PDF7
- 04Sign PDF9
- 05Redact PDF11
- 06Extract Pages13
- 07Password Protect15
- 08Common workflows18
- 09Troubleshooting & common questions21
- 10Quick reference cheat sheet24
01
How LocalPDF works
LocalPDF processes your files entirely inside your browser using pdf-lib.js — an open-source PDF library that runs locally. Nothing is sent to any server, at any point, for any reason.
When you open LocalPDF.html and drop in a PDF, the file is read into your browser's memory using the Web File API. All operations — merging, splitting, signing, redacting, extracting, encrypting — happen inside that memory using JavaScript running on your own machine. The result is written directly to a download. Your file never moves beyond your device.
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How to verify this yourself
Open LocalPDF.html, then open your browser's developer tools (F12 or Cmd+Option+I). Go to the Network tab and clear it. Drop in a PDF and run any operation. Watch the network requests. You will see zero outbound requests. Nothing leaves your machine.
What pdf-lib.js can and cannot do
pdf-lib.js is a mature, full-featured library that handles the vast majority of real-world PDFs. However, there are some limitations to know about:
| Scenario | What happens |
|---|
| Standard PDF | Works perfectly — merge, split, sign, redact, extract, protect all function as expected. |
| Password-protected PDF | You must remove the password first. LocalPDF cannot process an encrypted PDF without the owner password. Use the Password Protect tool in reverse — some tools like Adobe Reader let you save an unprotected copy. |
| Scanned PDF (image-only) | All tools work on the file structure. However, redaction draws boxes over the image pixels — text underneath is visually covered but not removed at the character level since there is no text layer. For maximum security on scanned documents, redact then flatten. |
| Very large PDFs (100MB+) | Processing depends on your device's available memory. Most modern computers handle this fine. If the browser tab crashes, close other tabs and try again. |
| PDF/A or PDF/X files | These are archival formats with strict standards. LocalPDF can open and process them but the output may not maintain PDF/A or PDF/X compliance. |
Working offline
Once LocalPDF.html is loaded in your browser, it works completely offline. The Google Fonts used in the interface are the only external resource — if you're offline when you first open it, the fallback system fonts are used instead. All PDF processing runs entirely offline regardless.
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Keep your LocalPDF.html file safe
LocalPDF is a single HTML file — your entire purchase lives in that one file. Back it up to a second location (cloud storage, external drive, email to yourself). If you lose it, contact hello@firstlocal.studio with your Gumroad receipt and we'll resend it.
02
Merge PDFs
Combine any number of PDFs into a single file. You control the order before merging.
How to use it
1
Open the Merge tab
Click "Merge PDFs" in the top navigation.
2
Add your files
Drag and drop PDFs onto the drop zone, or click it to open the file picker. Add as many as you need — they appear as a list below.
3
Set the order
Use the up ↑ and down ↓ buttons on each file card to reorder them. The merged PDF will follow this order top to bottom.
4
Merge and download
Click "Merge PDFs." The combined file downloads immediately to your device. The originals are untouched.
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Adding files one at a time
You can drop files onto the zone multiple times — each drop adds to the existing list rather than replacing it. This is useful if your files are in different folders.
03
Split PDF
Break a PDF apart — either every page into its own file, or into specific page ranges you define. Multiple output files download as a ZIP.
Split modes
Split all pages — Every page becomes its own PDF. A 12-page document produces 12 individual files, named page-1.pdf through page-12.pdf, delivered as a ZIP.
Custom ranges — Define exactly which pages group together. Enter ranges in the text field using the syntax below, then click Split.
Range syntax
1-3 → pages 1, 2, 3 as one file
4-6 → pages 4, 5, 6 as one file
7 → page 7 alone as one file
1-3, 4-6, 7 → three output files
1, 3, 5, 7 → four single-page files (non-contiguous)
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Pages not covered by any range are excluded
If your PDF has 10 pages and you define ranges 1-3 and 7-9, pages 4, 5, 6, and 10 will not appear in any output file. If you need all pages covered, make sure every page is included in at least one range.
04
Sign PDF
Draw your signature directly in the browser, then click anywhere on any page to place it. No upload, no account, no digital certificate required.
How to use it
1
Load your PDF
Drop the document onto the Sign tab drop zone.
2
Draw your signature
Use your mouse or trackpad to draw in the signature pad. Take your time — slow strokes produce cleaner results. Click "Clear" to start again.
3
Adjust size and opacity
Use the sliders to set the signature size and transparency before placing.
4
Place on the document
Click the page preview where you want the signature. It appears at that location. Click elsewhere to move it. Repeat for additional pages.
5
Save and download
Click "Apply Signature" to embed it permanently into the PDF and download the signed file.
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Getting a clean signature
Sign slowly and deliberately. The pad captures every movement, so a natural writing pace produces the most natural result. If you have a stylus or drawing tablet, use it — the quality difference is significant.
05
Redact PDF
Draw permanent black boxes over sensitive content. The redaction is embedded into the PDF as an object — it is not a visual overlay that can be removed by selecting and deleting.
How to use it
1
Load your PDF
Drop the document onto the Redact tab drop zone. A page-by-page preview appears.
2
Draw redaction boxes
Click and drag over any area you want to redact. A black rectangle appears. Repeat for as many areas and pages as needed.
3
Review your boxes
Scroll through all pages to confirm every sensitive area is covered before downloading.
4
Apply and download
Click "Apply Redactions." The boxes are embedded and the redacted PDF downloads.
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Scanned documents — an important distinction
A scanned PDF is an image, not text. LocalPDF's redaction draws solid black rectangles over the image pixels, covering the content visually. However, the original image data may still technically exist in the file depending on how the PDF is structured. For the highest security on scanned documents containing sensitive information — medical records, financial statements, legal documents — consult a specialist redaction tool that specifically flattens and removes underlying image data.
06
Extract Pages
Pull specific pages from a PDF into a new, standalone file. The original document is untouched.
Page syntax examples
1, 3, 5 → extracts pages 1, 3, and 5 into one PDF
2-8 → extracts pages 2 through 8
1, 5-8, 12 → extracts pages 1, 5, 6, 7, 8, and 12
10-1 → not supported — use ascending order only
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Extract vs Split — which to use
Use Extract when you want a single output file with specific pages — e.g. pulling the signature page from a contract, or extracting a chapter from a report. Use Split when you want each range as its own separate file — e.g. distributing different sections to different people.
07
Password Protect
Encrypt your PDF using AES-128. Set an open password, an owner password, or both — and control exactly what recipients can do with the file.
Understanding the two passwords
PDF encryption uses two separate passwords with different roles. You can set one or both:
| Password type | What it controls | When to use it |
|---|
| Open password | Prevents anyone from opening the file without it | Sending confidential documents — the recipient needs this password to view the file at all |
| Owner password | Prevents changing permissions or removing encryption | Always set this to something different from the open password — it ensures you retain control over the document's security settings |
⚠️
Set both passwords — and make the owner password different
If you only set an open password and leave the owner password blank, some PDF readers allow the encryption settings to be changed by anyone who can open the file. Always set a separate, strong owner password to retain full control.
Permissions explained
| Permission | When disabled |
|---|
| Printing | Recipients cannot print the document — they can only view it on screen |
| Copying text | Selecting and copying text from the document is blocked in compliant PDF readers |
| Modifying | Recipients cannot add, remove, or change content in the document |
| Annotating | Recipients cannot add comments, highlights, or annotations |
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Password strength indicator
LocalPDF shows a strength indicator as you type your password. For sensitive documents, aim for at least "Strong" — a mix of upper and lowercase letters, numbers, and symbols, at least 12 characters long. Short or common passwords can be brute-forced regardless of AES encryption.
08
Common workflows
Most real tasks combine more than one tool. These workflows cover the situations that come up most often.
You've received a contract as a PDF, reviewed it with ClauseGuard, negotiated the terms, and now need to sign and return it.
- Open LocalPDF → Sign tab. Drop the contract in.
- Draw your signature in the pad, set the size, and place it on the signature line.
- Download the signed PDF.
- If the contract contains financial details or personal information the other party doesn't need, open the Redact tab. Load the signed PDF and black out those sections.
- Send the final file. Your signature is embedded — nothing was uploaded anywhere.
You need to send multiple documents as a single secured file — a media kit, a proposal, a set of financial statements.
- Open LocalPDF → Merge tab. Add all files and set the order.
- Download the merged PDF.
- Switch to the Password Protect tab. Load the merged file.
- Set an open password to share with the recipient and a separate owner password to retain control.
- Disable copying and modifying if this is a read-only deliverable.
- Download the encrypted package and send.
You have a large report, contract, or manual and need to share only one section with someone — without giving them the whole document.
- Open LocalPDF → Extract Pages tab. Drop in the full document.
- Note the page numbers for the section you need.
- Enter the range — e.g.
14-22 — and click Extract.
- The extracted section downloads as a standalone PDF. The original is untouched.
You need to share a tax return or financial statement but want to redact sensitive account numbers, SSN, or other data before sending.
- Open LocalPDF → Redact tab. Drop in the document.
- Draw black boxes over every field you want to hide — account numbers, SSN, personal details.
- Apply the redactions and download the redacted file.
- Switch to Password Protect. Load the redacted file and encrypt it with a strong open password.
- Share the file and communicate the password via a separate channel (text message, phone call — not the same email).
09
Troubleshooting & common questions
Answers to the questions and issues that come up most often.
The file won't load
Most load failures are caused by the PDF being password-protected. Open the file in a PDF reader first, enter the password, and save an unprotected copy. Then load that copy into LocalPDF.
If the PDF was created by a very old or non-standard tool, it may use a PDF format that pdf-lib.js doesn't support. Try opening it in Adobe Acrobat or your operating system's built-in PDF viewer and saving a fresh copy — this re-encodes it in a standard format.
My merged PDF looks wrong or missing content
This occasionally happens with PDFs that use proprietary fonts that aren't embedded in the file. The underlying content is correct but may render differently in the output. Open the source files in a PDF reader and check that fonts are embedded before merging (File → Properties → Fonts in most PDF readers).
My signature looks thin or unclear
Sign slowly. The pad captures velocity as well as position — a slow, deliberate stroke produces a thicker, more natural result. Use a stylus if you have one. You can also increase the opacity slider to make a faint signature more visible.
The redaction boxes moved when I opened the result
Redaction boxes are embedded relative to the PDF page coordinates, not the screen preview. If the output PDF looks different from the preview, it is typically because the original PDF had a non-standard page rotation or origin point. Check the output file in multiple PDF readers — most will display it correctly.
Can I remove a password I set?
Yes — load the encrypted PDF into the Password Protect tab, enter the owner password to unlock it, and save a new copy with no password set. You must have the owner password to do this.
Does LocalPDF work on mobile?
LocalPDF works in mobile browsers (Safari on iOS, Chrome on Android) for most tools. Signing is significantly easier with a stylus. Very large files may be slow on older devices due to memory constraints. The desktop experience is more reliable for complex workflows.
I lost my LocalPDF.html file
Email hello@firstlocal.studio with your Gumroad receipt and we will resend the file. Keep a backup copy in cloud storage or a second drive.
Is this a legal electronic signature?
LocalPDF creates an image-based signature — your handwriting embedded as a graphic in the PDF. This is legally recognised for most business contracts in most countries under e-signature legislation (eIDAS in Europe, ESIGN and UETA in the US). However, some regulated industries and high-value transactions require a cryptographic digital signature with PKI verification (the kind DocuSign and Adobe Sign provide). Check your contract's specific requirements if in doubt.
10
Quick reference
Everything at a glance.
⊕ Merge PDFs
Input2+ PDF files
Output1 merged PDF
LimitNo limit on files
ReorderUse ↑ ↓ on each file card
⊗ Split PDF
All pagesOne PDF per page → ZIP
CustomOne PDF per range → ZIP
Syntax1-3, 4-6, 7
Skipped pagesNot included in output
✍ Sign PDF
DrawMouse, trackpad, or stylus
PlaceClick page to position
Multi-pagePlace on multiple pages
Legal typeImage signature (not PKI)
⬛ Redact PDF
MethodClick + drag to draw box
Multi-pageDraw across all pages
Text PDFsStructurally embedded
Scanned PDFsVisual cover only
◫ Extract Pages
Output1 PDF with selected pages
Syntax1, 3, 5-8, 12
vs SplitOne file out (not ZIP)
OriginalAlways untouched
🔒 Password Protect
EncryptionAES-128
Open passwordRequired to view file
Owner passwordRequired to change settings
PermissionsPrint, copy, modify, annotate