It's not revolutionary – no offense intended. There have been a ton of companies that built products like they did that are far more sophisticated with comparably simple getting started experiences.

For example, Cloud9 IDE (c9.io) had (and has) a fully functioning (custom) IDE in the browser, with syntax highlighting, autocompletion, debugger w/ breakpoints, and a terminal/REPL: https://web.archive.org/web/20170201175009/https://c9.io/ - fully functional in 2016, and earlier. I was part of the team at AWS that acquired the company that year [1], which is now an AWS product: https://aws.amazon.com/cloud9/ - they made it trivial to click a button and boot a workspace with a sample Python, Ruby, JavaScript app, etc., and then start hacking on it using the IDE or web-based terminal/CLI. (The latter alone is a very difficult thing to build in a web browser! Not to mention syntax highlighting for many languages, autocompletion, etc. – though Language Server Protocol implementations were a help for adding basic auto completion IIRC).

The Cloud9 IDE was sufficiently mature that the Cloud9 team used it to build their own product.

GitHub has also launched Codespaces which loads a repository as a VS Code IDE in your browser [2]: https://github.com/features/codespaces

And there are a number of other companies that provide similar products.

Maybe Repl.it hit some sweet spot of user experience that the others haven't, but – I mean no offense – I don't see what's innovative about it compared to the numerous other products I came across while doing market research back then. (I don't recall all the names.) It looks more like an IDE now than it did a year or two ago, but it seems to be behind Cloud9's capabilities as of 2016, not to mention the present version of AWS Cloud9 and CodeSpaces.

I feel I might be "that guy" who's calling Dropbox a dumb idea, but I'm skeptical that a revenue stream will materialize to justify the valuation. Tools like Repl.it, Cloud9 IDE, and CodeSpaces seem to me like features, not products.

Large corporations aren't going to want their proprietary codebase uploaded to a third party cloud service. GitHub (Microsoft) and Amazon have overcome that trust hump; and both have many developer-oriented products where these online coding tools are one feature among a large product suite, where it can be connected to continuous build and integration systems that deploy code to their clouds.

The largest addressable market for a standalone product that software development shops aren't actually going to use for real software development might be teaching students, which is not a large market. Cloud9 IDE tried that play and the market wasn't large enough to justify a startup, which is why I assume the founders & board of Cloud9 approved AWS's acquisition offer.

I haven't used Repl.it's product recently. What's the differentiator? What's the moat? I'm sorry to be a downer in a forum where we're meant to cheer startups (especially an HN startup); I'm only trying to offer rational analysis. Repl.it must be doing something unique right to be growing enough to garner such an investment. (Wasn't Repl.it just like ~3-5 people a year or two ago?)

On the other hand, this could be the VCs and founders making a play hoping one of the tech giants will acquire them. But Microsoft and Amazon already have equivalents and would likely not be interested. Maybe Salesforce or Google? I don't see this growing to become a public company without substantial diversification of the feature into a product suite that's sticky with enterprises. Maybe they've got a roadmap... would be interesting to see the pitch deck for this investment round.

[1] https://techcrunch.com/2016/07/14/amazons-aws-buys-cloud9-to...

[2] VS Code is an Electron web app compiled to run natively, which is presumably how GitHub got it running in the browser – especially given that as a Microsoft subsidiary they could presumably tap Developer Division's help.