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Sumatra PDF VS Keylight.dev

Compare Sumatra PDF VS Keylight.dev and see what are their differences

Sumatra PDF

Sumatra PDF is a slim PDF/DjVu/EPUB/XPS/CHM/CBR/CBZ/MOBI viewer for Windows.

Rating
0 reviews
Alternatives Is it good?
Keylight.dev

The simplest way to license your app.

Rating
5.0 · 1 review
Pricing
Open source Freemium $19 / Monthly (Up to 2000 licenses active.)
Alternatives Is it good?
ASocks
Clear, Fast & Unlimited. Residential & Mobile Proxies For Best Price. sponsored
Note: These products don't have any matching categories. If you think this is a mistake, please edit the details of one of the products and suggest appropriate categories.

Which is more popular?

Based on our record, Keylight.dev should be more popular than Sumatra PDF. It has been mentioned 4 times since March 2021.

social mentions
1 vs 4
PDF Tools popularity
100% vs 0%
alternatives listed
240+ vs 1

Base details

Website, pricing, platforms and company facts side by side.

Sumatra PDF
Keylight.dev
Website sumatrapdfreader.org keylight.dev
Pricing —
Open source Freemium $19 / Monthly (Up to 2000 licenses active.) Official pricing
Platforms —
Web
Company — Startup from Belgium · 1 - 9 employees · 2026
Listed in
PDF Readers And Editors PDF Tools PDF Reader eBook Reader +1
Developer Tools Software Development License Management Productivity Tech Web App Tool +4

About Sumatra PDF and Keylight.dev

In their own words, as submitted to SaaSHub.

Sumatra PDF
Keylight.dev

No description of Sumatra PDF yet.

Keylight sits between your payment provider and your app. Licenses, activations, customers, and usage all live here. Switch providers, or run several, without shipping a new build.

Read more about Keylight.dev

Features and specs

What each product offers, as listed by its team.

Sumatra PDF 6 features
Keylight.dev 16 features
  • Lightweight
    Sumatra PDF is known for its small footprint, making it quick to download and install. It runs efficiently on older hardware.
  • Speed
    The application is fast to open and navigate, even with large PDF files, enhancing the user experience.
  • Simplicity
    Sumatra PDF offers a minimalistic interface that is easy to navigate for users who need a straightforward PDF reader without unnecessary features.
  • Portable Version
    Sumatra PDF offers a portable version that can be run without installation, ideal for use on multiple computers or USB drives.
  • Free and Open Source
    The software is free to use and open-source, allowing users to inspect the code and contribute to its development.
  • Support for Multiple Formats
    In addition to PDFs, Sumatra PDF supports ePub, Mobi, XPS, DjVu, CHM, and comic book formats (CBZ and CBR), making it versatile.

Possible disadvantages

  • Limited Features
    Sumatra PDF lacks advanced features such as form filling, text editing, and annotations, which are available in other PDF readers.
  • No Document Editing
    The application does not support document editing, which can be a drawback for users needing to make changes to their PDFs.
  • Basic User Interface
    The simplistic design might not appeal to users who prefer a more modern or visually appealing interface.
  • Restricted Customization
    Sumatra PDF offers limited customization options, providing fewer settings and user preferences compared to other PDF readers.
  • No Cloud Integration
    The software lacks integrated support for cloud storage services, which can be inconvenient for users who manage documents online.
  • No Advanced Security Features
    Sumatra PDF does not include advanced security features such as digital signatures or encryption, which are essential for some professional users.
  • License Management
    Create, validate, revoke, and manage software licenses from one dashboard.
  • Device Activations
    Limit how many devices can use a license and manage individual activations.
  • Offline Access
    Keep apps working securely without a constant internet connection using signed offline leases.
  • License States
    Handle trial, free, paid, expired, limited, and grace-period access through one consistent state.
  • Payment Provider Integrations
    Connect Stripe, Paddle, Lemon Squeezy, Polar, Gumroad, and other payment platforms.
  • Provider Independence
    Change payment providers or use multiple providers without rebuilding your app’s licensing system.
  • Swift SDK Integration
    Add licensing to macOS and iOS apps using a native Swift package.
  • Secure License Validation
    Protect license data with cryptographic signatures and tamper-resistant validation.
  • Trials and Free Tiers
    Configure trials, free plans, fallbacks, and upgrade paths without building custom logic.
  • Customer Dashboard
    View licenses, customers, devices, activations, plans, and access status in one place.
  • License Analytics
    Track activations, active licenses, usage, and customer activity.
  • Key Rotation
    Rotate SDK signing keys without breaking older application versions.
  • Webhook Synchronization
    Convert payment, renewal, refund, cancellation, and subscription events into license updates.
  • Device-Bound Storage
    Store license data securely on the customer’s device without unnecessary Keychain prompts.
  • REST API
    Connect custom backends, checkout systems, and internal tools to Keylight.
  • Agentic Orchestration
    CLI usable by AI Agents to run the whole setup and more.

Analysis

An editorial look at what each product does well and who it suits.

Sumatra PDF
Keylight.dev

Overall verdict

  • Sumatra PDF is a great choice for anyone looking for a reliable and efficient PDF reader. Its performance, coupled with its simplicity, makes it a top recommendation for those who need a no-frills document viewer.

Why this product is good

  • Sumatra PDF is considered good because it is lightweight, fast, and easy to use. Its simplicity and minimalistic design make it an excellent choice for users who need a straightforward PDF reader without any unnecessary features. It has a quick load time and supports a variety of document formats including PDF, ePub, MOBI, CHM, XPS, DjVu, CBZ, and CBR. Additionally, it is open-source and doesn't require installation, making it ideal for users who prioritize portability.

Recommended for

    Sumatra PDF is especially recommended for users who need a fast and lightweight PDF reader with basic functionalities. It's ideal for those who want a simple tool for reading PDFs and other document formats without the complications of advanced features. It is also suitable for users who value open-source software.

Overall verdict

  • I don't have verified, up-to-date information about Keylight.dev specifically, so I can't confirm its quality, features, or reliability. It may be a newer or niche tool that isn't well-documented in my training data. I'd recommend checking recent user reviews, the official website's documentation, and community forums (like GitHub, Reddit, or Twitter) for firsthand feedback before making a decision.

Why this product is good

  • Unable to verify specific features, pricing, or performance claims for this product
  • No confirmed user reviews or independent testing data available
  • Cannot confirm company legitimacy, support quality, or security practices without direct verification

Recommended for

  • Users willing to conduct their own due diligence by visiting the official site directly
  • Developers who can test the product via a free trial or demo before committing
  • Anyone who checks third-party review sites, GitHub issues, or community discussions for real user experiences

Videos

Walkthroughs and reviews on video.

Sumatra PDF 2 videos + Add
Keylight.dev 0 videos + Add

Sumatra PDF my favorite PDF reader for Windows

More videos

  • - Sumatra PDF A FREE Portable PDF reader for Windows 10 | Alternative To Adobe PDF Reader

No Keylight.dev videos yet. You could help us improve this page by suggesting one.

Category popularity

How often each product is chosen within a category, 0–100% relative to the other.

Score bands 0–20 21–40 41–50 51–60 61–100
Sumatra PDF
Keylight.dev
100% 100%
PDF Tools
0% 0%
0% 0%
Tool
100% 100%
100% 100%
PDF Editor
0% 0%
0% 0%
Productivity
100% 100%

Questions & Answers

As answered by people managing Sumatra PDF and Keylight.dev.

What makes your product unique?

Keylight.dev's answer:

Keylight keeps app licensing separate from payments. You can use Stripe, Paddle, Lemon Squeezy, Polar, Gumroad, or your own checkout without tying your app to one provider.

It handles license keys, device activations, trials, free tiers, offline access, grace periods, and signed license state through one SDK.

Why should a person choose your product over its competitors?

Keylight.dev's answer:

My goal is to make all apps work with Keylight. So all of your licenses, from any types of apps, is going through Keylight for analytics, customer portal, support, ...

Most licensing tools are bundled into a payment provider. Keylight is built as an independent licensing layer.

That means you can change payment providers, sell through multiple platforms, or change your pricing model without rebuilding licensing inside your app.

It also gives developers a ready-made SDK and dashboard instead of requiring them to build and maintain their own licensing backend.

How would you describe the primary audience of your product?

Keylight.dev's answer:

Keylight is primarily built for independent developers and software companies selling apps directly to customers.

Its main audience includes:

macOS and iOS developers Web app and SaaS developers Developers selling outside app stores Teams migrating from a payment provider’s built-in licensing Developers who need trials, device limits, offline access, and license analytics

What's the story behind your product?

Keylight.dev's answer:

Keylight started because I kept rebuilding the same licensing systems for different apps: license keys, trials, activations, offline access, device changes, and all the edge cases that come with them.

I also did not want licensing to be controlled by whichever payment provider an app happened to use.

So I built Keylight as a standalone layer between the app and the payment provider. Payment platforms send events to Keylight, and the app receives one consistent license state through the SDK.

Who are some of the biggest customers of your product?

Keylight.dev's answer:

That's confidential.

Which are the primary technologies used for building your product?

Keylight.dev's answer:

Swift and Swift Package Manager for the Apple SDK Rust SDK / JS SDK / C# SDK / C++ SDK TypeScript React Next.js Stripe Connect and payment-provider webhooks Cryptographic signatures for secure, offline-capable licenses REST APIs for application and provider integrations

User comments

Share your experience with using Sumatra PDF and Keylight.dev. For example, how are they different and which one is better?

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Reviews and articles

External articles and on-site reviews we used to compare the two products.

Sumatra PDF no reviews yet
Keylight.dev 5.0 · 1 review

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Social recommendations and mentions

Recommendations tracked on public social media and blogs since March 2021.

Sumatra PDF 1 mention
Keylight.dev 4 mentions
  • anyone know any good epub/pdf readers for windows 11?
    You can use your browser for both, there are extensions(FireFox - PDF & EPUB/Chrome - PDF& EPUB) for that. In case, you want you use a separate software for them, I suggest SumatraPDF--it handles both PDFs and .EPUB files. Source: over 3 years ago
  • How offline license activation actually works
    You don't want to hand-roll Ed25519 and lease parsing. Most licensing SDKs hide this behind a couple of calls. With Keylight, for example, the offline path collapses to: activate once, then a local checkOnLaunch() that verifies the lease... - Source: dev.to / 3 months ago
  • I compared the licensing tools for my indie Mac app — the honest breakdown
    Full disclosure: I now build Keylight, so weigh this accordingly — I'm telling you the seam it's designed for, not that it wins every row. - Source: dev.to / 3 months ago
  • How to add license keys to a SwiftUI macOS app (in under an hour)
    Full docs and the free tier are at keylight.dev. If you're on Tauri or Electron instead of native Swift, the same SDK pattern exists in JS/Rust. - Source: dev.to / 3 months ago

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Alternatives to Sumatra PDF and Keylight.dev

When comparing Sumatra PDF and Keylight.dev, you can also consider the following products.

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