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Rectangle VS Underlayer

Compare Rectangle VS Underlayer and see what are their differences

Rectangle

Window management app based on Spectacle, written in Swift.

Rating
0 reviews
Pricing
Open source
Alternatives Is it good?
Underlayer

Build courses by API, drop them into your product with one iframe, and get told who finished. No portal, no learner accounts, priced per course view.

Rating
0 reviews
Pricing
Freemium $149 / Monthly
Alternatives Is it good?
FlexiQuiz
FlexiQuiz is a powerful online test generator that enables you to create engaging online quizzes, tests, or exams in minutes. Choose from 100's of features to create a customized quiz that meets your objectives for business, education, or fun. 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, Rectangle seems to be more popular. It has been mentioned 480 times since March 2021.

social mentions
480 vs 0
Mac Tools popularity
100% vs 0%
alternatives listed
240+ vs 2

Base details

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

Rectangle
Underlayer
Website rectangleapp.com underlayerhq.com
Pricing
Open source
Freemium $149 / Monthly Official pricing
Company — Startup from the United Arab Emirates · 1 - 9 employees · 2026
Listed in
Mac Tools Window Manager Mac Developer Tools +1
Education E-learning Education / E-Learning

About Rectangle and Underlayer

In their own words, as submitted to SaaSHub.

Rectangle
Underlayer

No description of Rectangle yet.

Underlayer is headless, API-first training for SaaS products. Instead of sending your users to a separate LMS portal, you generate a course, embed it where they already work, and get every completion sent back to your own systems. How it works Create a course. Generate one from a doc or a prompt...

Read more about Underlayer

Features and specs

What each product offers, as listed by its team.

Rectangle 5 features
Underlayer 0 features
  • Ease of Use
    Rectangle offers an intuitive user interface that makes window management straightforward and user-friendly.
  • Customizable Shortcuts
    Users can easily configure keyboard shortcuts to better suit their workflow, making window management faster and more efficient.
  • Free
    Rectangle is available for free, making it accessible to anyone without the need for a financial investment.
  • Frequent Updates
    The app receives regular updates, introducing new features and ensuring compatibility with the latest macOS versions.
  • Lightweight
    Rectangle is a lightweight application that doesn't consume many system resources, ensuring smooth performance even on older Macs.

Possible disadvantages

  • Limited Advanced Features
    Rectangle lacks some of the more advanced features found in paid window management applications, such as multiple monitor support and more complex window arrangements.
  • MacOS Only
    Rectangle is only available for macOS, so users of other operating systems are unable to take advantage of its features.
  • Occasional Bugs
    Some users report occasional bugs or unpredictable behavior, which might require troubleshooting or waiting for a future update.
  • Learning Curve for Shortcuts
    While customizable shortcuts are a benefit, there is an initial learning curve for users to memorize and effectively use these shortcuts.
  • Basic Aesthetic
    The app's design and aesthetic are quite basic, lacking the polish and visual appeal found in some other similar tools.

No features have been listed yet.

Analysis

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

Rectangle
Underlayer

Overall verdict

  • Overall, Rectangle is highly regarded for its ease of use, extensive customization options, and the fact that it is free and open-source. It provides essential functionality without unnecessary complexity, making it suitable for both casual users and power users who need efficient window management.

Why this product is good

  • Rectangle is a popular window management tool for macOS, known for its simplicity and ease of use. It allows users to efficiently organize and resize application windows using customizable keyboard shortcuts or by dragging windows into pre-defined areas of the screen. This can enhance productivity by minimizing the time spent arranging windows and improving multitasking capabilities.

Recommended for

    Rectangle is recommended for macOS users looking for a straightforward, lightweight solution to manage application windows. It is particularly beneficial for those who frequently work with multiple applications at once, including developers, designers, and anyone who values a tidy and organized desktop environment.

No analysis of Underlayer yet.

Videos

Walkthroughs and reviews on video.

Rectangle 3 videos + Add
Underlayer 1 video + Add

SKYWALKER RECTANGLE TRAMPOLINE REVIEW!!!

More videos

  • - Skywalker Rectangle Trampoline Review #1
  • - Marvin Malton 160 Rectangle Flying Hour Watch Review

Underlayer demo

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
Rectangle
Underlayer
100% 100%
Mac Tools
0% 0%
0% 0%
Education
100% 100%
100% 100%
Window Manager
0% 0%
0% 0%
E-learning
100% 100%

Questions & Answers

As answered by people managing Rectangle and Underlayer.

Who are some of the biggest customers of your product?

Underlayer's answer:

it's pre-launching

What makes your product unique?

Underlayer's answer:

Underlayer is training with no portal. You build a course by API, by MCP, or in the visual builder, and add it to your product with one iframe. Then signed webhooks tell your systems who finished. Learners never create an account or leave your app, and the player uses your theme, so it looks like part of your product. We charge per course view, not per seat, and every price and overage rate is published.

Why should a person choose your product over its competitors?

Underlayer's answer:

Most course tools, like Coassemble, Trainn and LearningStudioAI, assume training happens on their own site: learners sign up, log in and get enrolled, and you pay per seat. Underlayer takes the opposite approach:

No learner accounts. You pass in your own user IDs and we track progress against them. Built for developers. A full REST API covers every resource, and an MCP server lets AI agents create and edit courses. Results in your own tools. Signed webhooks send completions to your CRM, your product or your data warehouse. SCORM 1.2 and 2004 export for customers who still need to load courses into an LMS. Public pricing. Plans start at $149/month for 25,000 course views, with unlimited learners and no sales call required.

How would you describe the primary audience of your product?

Underlayer's answer:

SaaS product, customer success and engineering teams who want onboarding, product education or compliance training inside their own app. It also suits platforms that train other people's users, like partner networks, marketplaces and field-ops tools, where a separate LMS login gets in the way.

What's the story behind your product?

Underlayer's answer:

Every company putting training in front of its users hit the same wall: the LMS wanted to own the learner. That meant a separate portal, a second login and a per-seat bill for people who never opened a course. We built Underlayer as the layer underneath instead. You keep the product and the user relationship. We handle building the course, playing it and tracking progress, and we stay out of the way.

Which are the primary technologies used for building your product?

Underlayer's answer:

Next.js 16 (App Router) with React 19 and TypeScript, Tailwind CSS v4, and Supabase (Postgres with row-level security, Auth and Storage). Claude from Anthropic generates courses with AI. Stripe handles billing and Resend sends email. There is also a remote MCP server with OAuth 2.1 for AI-agent access.

User comments

Share your experience with using Rectangle and Underlayer. 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.

Rectangle no reviews yet
Underlayer no reviews yet
  • Best 6 Mac Window Managers
    mackeeper.com · Sep 2023

    Rectangle shows that you don’t need to dip into your bank account to get window resizer tools. This free Mac window manager lets you manage multiple windows using keyboard shortcuts, menu options, or by dragging and...

  • Top 6 Window Manager Apps for Mac
    www.maketecheasier.com · May 2023

    Most window manager apps for Mac support multiple monitors. They can help you move windows between screens and create custom layouts for each monitor. Many window manager apps – such as BetterSnapTool, Magnet, and...

  • The 6 Best Mac Window Management Tools
    www.makeuseof.com · Apr 2023

    However, it might take some time for you to get used to the shortcuts in the Rectangle app since there are many. Furthermore, you can also add some of your apps to exceptions if you want to keep them away from...

We have no reviews of Underlayer yet. Be the first one to post

Social recommendations and mentions

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

Rectangle 480 mentions
Underlayer 0 mentions
  • Apple introduces M6 and M5 Ultra for a big leap in performance and AI compute
    Rectangle solved my macos window management annoyances. https://rectangleapp.com/ Not involved in dev of this, just a happy user. - Source: Hacker News / about 2 months ago
  • Ubuntu 26.04 LTS Released
    As a both old Linux and now decade user of MacOS, after I got used to no middle-click paste and no focus-follows-mouse: 1. Keyboard shortcuts are Emacs, Ctrl-A: start of line, E: end of line, K: kill selected or to end of line, Y to... - Source: Hacker News / 6 months ago
  • Native Instant Space Switching on macOS
    Every macOS user uses Rectangle.app — https://rectangleapp.com The ones who don't use it is because they don’t know it exists. - Source: Hacker News / 6 months ago

View more

Tracking Underlayer since Sep 2026.

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