Software Alternatives & Startups

BLOCK THIS! VS KeptPDF

Compare BLOCK THIS! VS KeptPDF and see what are their differences

BLOCK THIS! logo BLOCK THIS!

Block This 3.0 is a FREE and Open Source ad blocker for Android that works in all apps and browsers!

KeptPDF logo KeptPDF

Redact, edit, OCR, and sign PDFs entirely in your browser. The file never leaves your device. Free, no account needed.
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  • BLOCK THIS! Landing page
    Landing page //
    2023-08-26
  • KeptPDF Landing page
    Landing page //
    2026-08-22

KeptPDF is a PDF toolkit that runs entirely in your browser. Nothing uploads: every tool runs on your own device, so the document never touches a server.

What it does:

  • Redaction that auto-detects names, SSNs, phone numbers, addresses, and dates, then removes the underlying text instead of drawing a box over it. Every redacted file gets an audit certificate that anyone can verify.
  • OCR that makes scanned PDFs searchable, with on-device processing.
  • Sign, annotate, compare, organize, split, merge, compress, convert, watermark, Bates numbering, exhibit stamps, and more. About 25 tools in total.
  • A command line version runs the same redaction engine on your own servers for bulk work: scanning bureaus, litigation support teams, and records departments process thousands of PDFs in one pass.

Who it is for: law firms, accounting practices, clinics, and anyone who shares documents they cannot afford to leak.

The core tools are free with no sign-up. Works offline as an installable app.

BLOCK THIS!

Pricing URL
-
$ Details
Release Date
-

KeptPDF

$ Details
freemium $29 / Monthly (Pro, 1 user)
Release Date
2026 May
Startup details
Country
United States
State
Tennessee
Founder(s)
John Whitworth

BLOCK THIS! features and specs

  • Ad Blocking
    BLOCK THIS! effectively blocks ads, providing a smoother and less cluttered browsing experience.
  • Privacy Protection
    The app helps protect user privacy by blocking trackers and other intrusive scripts, which can help keep your personal information secure.
  • Bandwidth Saving
    By blocking ads and trackers, BLOCK THIS! reduces the amount of data loaded on webpages, saving bandwidth and potentially speeding up browsing.
  • Battery Efficiency
    Blocking ads can lead to less resource consumption, potentially extending the battery life of mobile devices.
  • Free to Use
    The app is available for free, making it accessible to a wide range of users without the need for a subscription or purchase.

Possible disadvantages of BLOCK THIS!

  • Compatibility Issues
    BLOCK THIS! may not work smoothly on all devices or with all browsers, which might limit its usability for some users.
  • Potential Content Blocking
    Occasionally, the app may block legitimate content along with ads and trackers, which can disrupt the user experience on some websites.
  • Updates and Support
    The frequency and reliability of updates and ongoing support can be variable, potentially leading to performance issues or lack of new features over time.
  • Root Requirement for Android
    On some Android devices, full functionality may require root access, which is not recommended for all users due to security and warranty concerns.
  • Potential Ethical Concerns
    Blocking ads raises ethical questions regarding the support of content creators who rely on advertising revenue to provide free content.

KeptPDF features and specs

  • Simple PDF Editing
    KeptPDF offers straightforward tools for editing, merging, splitting, and converting PDF files, making it accessible for users who need quick document management without a steep learning curve.
  • Web-Based Accessibility
    Being a web-based tool, KeptPDF can be accessed from any device with an internet connection, eliminating the need for software installation and allowing use across different operating systems.
  • Multiple File Format Support
    The platform supports conversion between PDF and various other file formats, offering flexibility for users who work with documents in different formats.
  • No Installation Required
    Since it operates in a browser, users can save storage space on their devices and avoid compatibility issues that sometimes arise with desktop software installations.
  • Quick Processing
    KeptPDF is designed to process PDF tasks efficiently, allowing users to complete common document tasks like compression or conversion in a relatively short amount of time.

Analysis of BLOCK THIS!

Overall verdict

  • BLOCK THIS! is considered a good option for users seeking a lightweight and effective method to block ads and enhance privacy protection. Its DNS-based blocking can be less intrusive compared to other ad-blockers.

Why this product is good

  • BLOCK THIS! is a tool designed to block unwanted ads and protect user privacy while browsing the internet. It uses DNS blocking to stop ads before they even reach the browser, which can improve page load times and reduce data usage. Additionally, it may provide some protection against malicious sites.

Recommended for

  • Users looking to speed up web browsing by reducing ads and other unwanted content.
  • Privacy-conscious users who want to avoid tracking by advertisers.
  • Individuals seeking a DNS-based ad blocking solution that works on multiple devices.

Category Popularity

0-100% (relative to BLOCK THIS! and KeptPDF)
Security & Privacy
94 94%
6% 6
PDF
0 0%
100% 100
Monitoring Tools
100 100%
0% 0
PDF Readers And Editors
0 0%
100% 100

Questions & Answers

As answered by people managing BLOCK THIS! and KeptPDF.

What makes your product unique?

KeptPDF's answer:

KeptPDF runs entirely in your browser. Your file, and the text inside it, never leaves your device. Not to an AI, not even to us. You can open your browser's network tab and watch: the document bytes never go out.

Most online PDF tools upload your file to a server first, and some "AI redaction" services quietly send your document text to a third-party model. That is the exact risk people are trying to avoid when they redact something.

KeptPDF also does true redaction. The text is removed from the file, not covered with a black box you can copy out later. Every redaction produces a verification certificate you can share with the file.

Why should a person choose your product over its competitors?

KeptPDF's answer:

Three reasons.

Privacy you can verify, not just a promise. Processing happens locally in the browser, so there is no upload step to trust. We do send anonymous usage counts for quota, and we say so plainly, but never your document.

Real redaction with proof. Removed text is permanently gone, and you get a certificate showing the file was checked for leftover extractable text. Automated detection cannot catch everything, so a final human review is still your job, and the tool says that too.

It works on a phone. Most PDF suites assume a desktop. KeptPDF was built and used on a phone first, so redacting a document while you are standing in a hallway actually works.

How would you describe the primary audience of your product?

KeptPDF's answer:

Anyone who has to hand a document to someone else and needs the sensitive parts gone first.

In practice that is solo attorneys and small law firms, accountants and tax preparers, healthcare and records staff handling requests, HR teams, and individuals dealing with their own medical, legal, or financial paperwork.

The common thread is not an industry. It is a person who cannot upload a confidential file to a random website, and who does not have an enterprise IT budget to solve it.

What's the story behind your product?

KeptPDF's answer:

A family member got seriously ill. We spent most days at the hospital, and straight answers were hard to come by, so we leaned on AI tools to make sense of the records, notes, and lab results.

But you cannot paste a medical record into an AI chat. You have to strip the names, the ID numbers, the diagnoses first. And almost every tool we found either wanted to upload the whole file to a server, or "auto-redacted" by sending the document text to an online AI. That was the exact thing we were trying to avoid.

Most of this was happening on a phone, at a bedside. So I built the tool I needed: redaction that runs on the device, works on mobile, and never sends the file anywhere. That turned into KeptPDF, which is now a full PDF suite with over 20 tools, all local-first.

Which are the primary technologies used for building your product?

KeptPDF's answer:

The app is plain JavaScript with no front-end framework, which keeps it fast and keeps the code auditable.

PDF work happens in the browser using pdf.js for rendering and pdf-lib for writing. Text recognition uses Tesseract running as WebAssembly. Password and encryption handling uses a WebAssembly build of qpdf. It is a Progressive Web App, so it installs and works offline.

The thin server side is Node on Vercel, with Postgres for accounts, Stripe for billing, and Resend for email. None of those ever see a document.

Who are some of the biggest customers of your product?

KeptPDF's answer:

KeptPDF is early and independent, and we do not publish customer names. The product is privacy-first by design: we never see your documents, and we do not track who our users are or what they work on. Publishing a client list would sit badly next to that.

The user base today is mostly solo attorneys, small firms, accountants, and individuals handling their own records.

User comments

Share your experience with using BLOCK THIS! and KeptPDF. For example, how are they different and which one is better?
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Social recommendations and mentions

Based on our record, BLOCK THIS! seems to be more popular. It has been mentiond 22 times since March 2021. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.

BLOCK THIS! mentions (22)

  • Blockada 5 alternative?
    Block This 3.1 VPN ad-blocker works just as well as adguard dns for older Android 8.0- OS. Very easy to use. Source: almost 3 years ago
  • Nightmare on my kindle fire 8
    Try installing block-this on it and see if it helps. Https://block-this.com. Source: over 3 years ago
  • Are the “Jesus” ads on this site getting more aggressive?
    For android devices block this is an app that can block nearly all mobile ads, both in apps and in browsers. Source: over 3 years ago
  • Appliance makers sad that 50% of customers won’t connect smart appliances
    I think https://block-this.com/ does what you propose. Source: over 3 years ago
  • Is possible to make a universal patch for no ads that work on every apk?
    Maybe check out the canonical page instead: https://block-this.com. Source: over 3 years ago
View more

KeptPDF mentions (0)

We have not tracked any mentions of KeptPDF yet. Tracking of KeptPDF recommendations started around Aug 2026.

What are some alternatives?

When comparing BLOCK THIS! and KeptPDF, you can also consider the following products

AdShield.ai - AI-powered placement exclusion lists for Google Display campaigns

Smallpdf - PDF document management and conversion suite

Ads-Shield - Ads-Shield: Content Blocker is an all-in-one ad-blocking app that stops all kinds of ads in your browser, Facebook, YouTube, and even other third-party apps.

iLovePDF - Premium online PDF tool set

Ad Skipper for YouTube - Ad Skipper for YouTube – Skip and Mute YouTube ads is a powerful Android tool specially designed for YouTube streaming lovers who want to enjoy the high-quality fast streaming experience without any irritation from ads.

Sejda - Split, merge and other powerful PDF tools.