
HackerRank
Project Euler
Codewars
Exercism
CodeForces
interviewing.io
Codecademy
Practice and level up your development skills and prepare for technical interviews.

Smartlook
SessionStack
WatchThemLive
Hotjar
Session Replay by Zarget
Microsoft Clarity
Inspectlet
#1 open source session recording & replay library

Which is more popular?
Based on our record, LeetCode seems to be more popular. It has been mentioned 544 times since March 2021.
Website, pricing, platforms and company facts side by side.
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| Website | leetcode.com | rrweb.com |
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In their own words, as submitted to SaaSHub.


No description of LeetCode yet.
Embeddable session replay infrastructure on the open source library the industry standardized on. Record and replay sessions inside your own product, through an unbranded SDK and API.
What each product offers, as listed by its team.


Possible disadvantages
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 rrweb yet.
Walkthroughs and reviews on video.
Is A LeetCode Premium Subscription Worth It?
More videos
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How often each product is chosen within a category, 0–100% relative to the other.


As answered by people managing LeetCode and rrweb.
rrweb's answer:
Most session replay vendors are building on the engine we maintain. Choosing rrweb means owning that layer directly.
What that gets you in practice: events are plain JSON, so you store them in your own S3, Postgres or stream, keep them in the EU, and delete them on your own schedule. There's no lock-in at the recorder, because if you leave rrweb Cloud your recordings still replay in an open source player. And the plugin API lets you capture things a closed SaaS recorder will never expose, including canvas, WebGL and custom event types.
Where a competitor wins: if you want replay bundled with product analytics, error monitoring and heatmaps in one dashboard, and you never want to think about infrastructure, a full suite like PostHog or Sentry does more out of the box. Several of them sponsor rrweb, and we'd rather people use the right tool than the closest one.
rrweb's answer:
Two groups.
Product engineers who need replay inside something they're already building: bug reporting, customer support tooling, QA, AI agent observability, interactive demos. They install the library, own the pipeline, and want format-level control.
Platform teams at companies whose product is replay, or includes it. Observability vendors, analytics suites, co-browsing and customer experience tools. They embed rrweb as the capture layer instead of writing a recorder from scratch, which takes years to get right across browsers, shadow DOM, canvas, iframes and web components.
rrweb's answer:
rrweb started in 2018 as one engineer's side project. Yanzhen Yu wanted to record and replay what users actually did in a browser, and published the result under MIT. There's a short documentary about how it came together, in Chinese with English subtitles.
Adoption moved faster than anyone planned for. A core team formed around the project in 2020, and Justin Halsall (Amsterdam), Eoghan Murray (Dublin) and Yun Feng (San Francisco) maintain it today alongside more than 100 contributors. The library now sits at close to 20,000 stars and powers the replay features inside some of the largest observability and analytics products on the market.
The awkward part of that success is that an MIT library carrying replay for billion-dollar companies was still being maintained on evenings and weekends. rrweb Cloud exists to fix that. It's the hosted version of the project, built by the maintainers, based in Amsterdam, and the logic is simple: revenue from Cloud pays for maintainer time on the open source library.
rrweb's answer:
The library is roughly 89% TypeScript, deliberately so. Record and replay share a strongly typed event schema, and those types are the contract between the two sides. The remainder is JavaScript, HTML test fixtures, and Svelte for the player UI.
Four packages:
rrweb-snapshot, which serializes the DOM and its state into a JSON tree and rebuilds it rrweb, the record and replay functions rrdom, a virtual DOM that makes replay faster and testable headlessly rrweb-player, the player UI
Underneath it leans on browser primitives: MutationObserver for DOM changes, event listeners for input, scroll and pointer activity, CSSOM for stylesheet state, and patched canvas contexts for 2D and WebGL capture. Events are plain JSON, optionally packed for transport.
Build and test tooling is Yarn, Turborepo, Vite, Vitest, Puppeteer for integration tests, and Changesets for releases. MIT licensed throughout.
rrweb's answer:
Sentry Datadog PostHog Amplitude Mixpanel New Relic Pendo Highlight Browserbase StatCounter Requestly Gleap Bird Eats Bug Navattic CUX UXWizz Analyzee SmartX
Sentry, PostHog, Pendo and Highlight also fund the project as sponsors on OpenCollective.
rrweb's answer:
rrweb is the recording engine most session replay products are built on. Sentry, PostHog, Pendo, Highlight, Mixpanel, Datadog, Amplitude and New Relic all ship replay built on rrweb or its approach.
It serializes the DOM into a typed JSON event stream: one full snapshot, then timestamped incremental mutations. There is no video. Replay rebuilds the actual page in a browser, so text stays selectable, CSS re-renders at any viewport, and a three-minute session weighs kilobytes instead of megabytes. Because the output is structured JSON, an LLM can read a session directly without a vision model in the loop.
It's MIT licensed with close to 20,000 GitHub stars, so the capture layer is yours to own. rrweb Cloud is the hosted backend from the same maintainers, for teams who don't want to run ingestion, storage and replay infrastructure themselves.
Share your experience with using LeetCode and rrweb. For example, how are they different and which one is better?
External articles and on-site reviews we used to compare the two products.


LeetCode is a renowned online platform offering a compendium of coding challenges that enable software developers to sharpen their programming prowess, facilitating their preparation for technical interviews. This...
What are LeetCode and LeetCode alternatives good for?LeetCode💡Interested in leveling up your career? Apply to the Formation Fellowship...
In the quest for coding excellence, developers often seek platforms that not only challenge their skills but also make the learning process engaging and fun. While Leetcode has been a staple in the coding community...
We have no reviews of rrweb yet. Be the first one to post
Recommendations tracked on public social media and blogs since March 2021.


General Coding Assessment (GCA): the harder of the two, but manageable with preparation. It's done on CodeSignal, either in person or online. To prepare, practice DSA questions on competitive programming sites like LeetCode, Codewars,... - Source: dev.to / 2 months ago
Category Tool URL How I used it General AI assistant ChatGPT Https://chatgpt.com Breaking down concepts, simulating interviewers, reviewing answers AI writing / reasoning Claude Https://claude.ai Refining behavioral stories and... - Source: dev.to / 5 months ago
Plain BST. Fine when input is random or the problem doesn't require worst-case guarantees. Tree problems on LeetCode typically assume balanced input and don't ask you to maintain balance yourself. - Source: dev.to / 5 months ago
Tracking rrweb since Mar 2021.
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