Review of CoderPad

Note: This post was adapted from an review I originally wrote on Quora.

I recently found out about CoderPad, a collaborative coding tool that lets you run your code as you go and is particularly handy for technical interviews. Here’s what I thought of it.

Interviewing is hard

I’ve been on both sides of the table for a fair amount of technical interviews—from phone screens and live coding rounds to in-person whiteboard sessions. For both the interviewee and the interviewer, the live coding round can be particularly draining for a variety of reasons.

As an interviewee, you’re faced with a variety of stumbling blocks during this round. For one, you’re working with an IDE or editor that’s likely an inferior version of what you’re used to. In a real-life situation, it’s also unlikely that you would write an entire function or class without testing it every so often. As a result, the cycles spent on working in an unfamiliar environment and without your usual testing routine can detract from what matters: showing what you can do.

As an interviewer, it’s a balancing act: staying engaged while a candidate muddles through a problem, keeping the candidate from straying too far down the wrong path, and stopping yourself from spoon-feeding them solutions. You’re simultaneously tracking their process—namely how long it took the candidate to to come up with a game plan, when they turned that game plan into a shitty solution, and when they took the clumsy solution and made it elegant. And unless you want to look like a n00b, you’ll have to be able to catch new bugs and evaluate creative solutions effectively.

Coding interviews are, at their best, a proxy for actual on-the-job aptitude. At their worst, they’re poor amalgams of real work environments where you’re stripped of the ability to syntax-highlight and run your damn code.

So, yeah, interviewing is hard.

The other guys

To address some of these issues, it helps to have a tool that can do some of the heavy lifting for you.

One of these tools is Google docs, which many companies still use to conduct live coding rounds. On the upside, Google docs can be extremely versatile and the ability to draw can come in handy if part of the coding round is conceptual or high level. Working against it: lack of indentation, line numbers, and syntax highlighting. Oh, and, you can’t run your code.

A big improvement over that is a tool called Collabedit. Collabedit has a slick UI and provides support for nearly every language you’d need. However, candidates still have to code blind—it can’t run code either.


Enter CoderPad. CoderPad is a collaborative editor with REPL built in. It’s not the first product to feature collaborative coding, and it’s not the first product to feature live REPL, but it is the first product I’ve seen that utilizes these two elements really, really well.

In other words, CoderPad allows both the interviewer and interviewee to run code as it’s being written.

Screen Shot 2013-08-14 at 9.39.41 PM

CoderPad supports a number of interpreted and compiled languages—which is pretty awesome. In addition to more closely mimicking how people actually work, it takes the heat off of the interviewer a bit so he can focus on whether the candidate is a good fit.

Cool features include:

  • Nice aesthetics: syntax highlighting, line numbers, indentation
  • Great language coverage for both compiled and interpreted languages including: JavaScript, Python, Ruby, Java, Scala, C/C++, and Go
  • Really beautiful/slick UI
  • Ability to include as many collaborators as you want
  • Playback feature so you can see how people got there, rather than just the end code
  • Reasonable pricing scheme

Some limitations/nice-to-haves:

  • Ability to add timestamps as the candidate works so you can track progression
  • Ability to unshare code with candidate after the interview is over
  • Faster compile times (interpreter is really fast)

Despite these minor limitations, as far as I know, there isn’t another collaborative coding tool with live REPL out there that approaches CoderPad’s level of polish and utility. You should give it a spin next time you’re interviewing someone.

Leave a Reply

XHTML: You can use these tags: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>