
Webpack
esbuild
Parcel
npm
RequireJS
stealjs
JSPM
Rollup is a module bundler for JavaScript which compiles small pieces of code into a larger piece such as application.

Coassemble
Trainn.co
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.
Which is more popular?
Based on our record, rollup.js seems to be more popular. It has been mentioned 68 times since March 2021.
Website, pricing, platforms and company facts side by side.
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| Website | rollupjs.org | underlayerhq.com |
| Pricing | ||
| Company | — | Startup from the United Arab Emirates · 1 - 9 employees · 2026 |
| Listed in |
In their own words, as submitted to SaaSHub.


No description of rollup.js 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...
What each product offers, as listed by its team.


Possible disadvantages
No features have been listed yet.
An editorial look at what each product does well and who it suits.


Overall verdict
Why this product is good
Recommended for
No analysis of Underlayer yet.
Walkthroughs and reviews on video.
No rollup.js videos yet. You could help us improve this page by suggesting one.
Underlayer demo
How often each product is chosen within a category, 0–100% relative to the other.


As answered by people managing rollup.js and Underlayer.
Underlayer's answer:
it's pre-launching
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.
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.
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.
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.
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.
Share your experience with using rollup.js and Underlayer. For example, how are they different and which one is better?
External articles and on-site reviews we used to compare the two products.


Rollup provides much simpler configuration over webpack 4 and has a host of pre-configured plugins that are a breeze to incorporate into your project. Rollup's also the fastest of the build tools period.
We have no reviews of Underlayer yet. Be the first one to post
Recommendations tracked on public social media and blogs since March 2021.


This article presents a bunch of ways how to find unused code, remove it, and configure tools and bundler to prevent dead code in the future. Sections for bundler are based on set of Vite, which under the hood delegates to Rollup in... - Source: dev.to / 4 months ago
The reality is simple: minification was never security. It's a size optimization that bundlers like esbuild, Webpack, and Rollup do by default. Variable renaming slows down human readers but LLMs read minified code like you read... - Source: dev.to / 7 months ago
Before addressing the solution, it's useful to contextualize the role of the bundler. In a modern frontend architecture, the bundler (such as webpack, rollup, or vite) has the task of traversing the application's dependency graph,... - Source: dev.to / 11 months ago
Tracking Underlayer since Sep 2026.
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An extremely fast JavaScript bundler and minifier
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