Live-coding conference talks

2024 / 02 / 04  •  Daniel Garnier-Moiroux

I love giving conference talks. My primary focus is demystifying how code works, or showing cool stuff. Some speakers go the safer way of pasting some code on slides: you only write the code once, give it an acceptable shape, and be done with it. No awkward fumbling and debugging live something that used to work, just yesterday, I SWEAR.

Personally, I can’t focus for 50 minutes on a slide deck chock-full of code. That’s because there’s very little rhythm in the code that gets shown. The speaker may be great, and may be able to make the rest of the presentation entertaining. But the code is very inert.

And I can’t consume inert code just by squinting at it in sequence - I need to build a mental model of how things fit together, I need to go back and forth, explore, make hypotheses, maybe experiment. And if someone is giving me a tour of the code instead, it should be a conversation, where I can rephrase what is explained to me and ask questions. This gives the other person some feedback to adjust their discourse, insist on this or that, speak at a different level of abstraction, etc. Which obviously does not happen when you’re showing slides to a room of 107 people.

So, while code-on-slides may be easier, or safer, that’s not what I like. I do enjoy a good live-coding demo though: I can see the speaker bringing thoughts to life, insisting on what is important, speeding through boilerplate and showing little experiments “but if I change that thing over here, then this happens, so that’s why XYZ is important.”

Live-coding is not easy. And you always face the risk of messing something up and fiddling with stuff for some very long seconds before finding your way. Nobody wants to watch you debug, live - we all debug all day long. What we want is code wizardry, the impression that everything makes so much sense, that it’s easy for the person doing it. Yep, they are juggling with 8 torches set on fire while horseback riding, easy. Surely, there are no horses or torches involved when on my daily, mundane commute to work with public transport.

But here’s a trick. It’s mostly a LOT of work. And a few guiding principles which can help a bit.

Tips and trick

Know your audience

Like every conference talk, you should start by defining who you are talking to, what you think they know or don’t know, what you know that they don’t - in short, what you can teach them, and how. Design your talk accordingly.

If you’re live-coding something Python at a Java conference, don’t go all-in on Python-centric features (looking at you, itertools).

If you’re at a Symfony conference, by all means, skip over all the basics of PHP and show them some advanced features!


Do you know how you juggle 8 torches? I don’t know the specifics, but I know you need to practice a lot. Until you don’t need to think about it.

Practice your talk. For a live-coding, depending on the talk, I usually practice it 10 to 20 times before delivering it - and that’s once I have a solid structure in place. I’m not good, I’ve just failed enough times that I know 99% of what can go wrong, and I can sleepwalk through the code. But when, occasionally, during the live presentation I stray, and something does go wrong, I can quickly fix it. Trust me, I have seen this exact error, in this exact place, multiple times, and I know the fix.

Lay out what you’re going to do

Just like in normal day-to-day coding, you don’t start hammering away at a problem. You think it through, model it, list edge cases. Before you dig into a live-coding, or a live-coding section, set up this way of thinking for your audience: “this is what I am going to show you, pay attention to this and that”.

For longer stretches of coding, I often lay out a “game plan” in comments:

//  1. Obtain authorization_code
//    a. Redirect the user to their Single-Sign-On provider
//    b. Obtain the authorization_code when they are redirected back
//  2. Exchange authorization_code for id_token
//  3. Read the data the id_token
//  4. Load the data in the session

As I code a small step, I can refer back to our game plan, and a ✅ emoji or something.

Practice again

No seriously. Until you’ve failed enough, you should practice. You will build confidence, and for good reason.

Sometimes you fail and you feel bad. That is what practice is for. Enough practice, spaced over time, will make you (almost) perfect.

Focus on concepts, not code

Hot take: code is an implementation detail of a good presentation. Sometimes it’s an important implementation detail, mind you. But what attendees want to learn is what can only be read between the lines: the hypotheses driving a particular implementation, why we choose to do something instead of something else, how it all fits together, etc.

Some bits of code are important, but you are mostly giving pointers so attendees take note and explore things in their own time, actually implementing stuff and going through docs.

The reason for doing it live-coding is to mimic real-life situations your attendees usually go through, build empathy, and entertain the audience by doing it flawlessly.

Practice more

I’ve already mentioned that, haven’t I?

Slow down

While presenting, make sure to take pauses. Breathe. Let the audience catch up with you, read the code, take some time to process it and open up the space for questions. I’m often guilty of shoving too much content within a 50-minute session. That is a VERY long time to be fully alert and absorb knowledge, even without mentioning the talks folks already attended before coming to yours!

Side benefit: it opens the door for questions, and interactions with the audience, which gives you immediate feedback on how things are going.

(I won’t repeat “practice” but you know I mean it 😀)

Have fun

Importantly: have fun! The audience came to have a good time. If you’re suffering all the way through your presentation, they will feel bad for you - not my definition of A Good Time™. Smiling and laughter are contagious, if you’re having fun, you are inviting attendees to share your joy of coding and making stuff.

As Josh Long puts it “Tech is boring. Make it fun.” And also Josh: “make fun of yourself, but never of others”.

But mostly, a lot of work

All of this will maybe help you, but as you’ve read multiple times, it’s all about the work you put in. You invest a lot of time into creating an interesting codebase, then crafting a story to tell around this technical artifact. It takes weeks, sometimes months, to come up with a good story.

And then, practice, practice, practice, until you can do it blindfolded.

Got some praise after my Carvel talk at Swiss Cloud Native Day. As I told folks at the conference: I had rehearsed fully the evening before, twice the day before that, once more the day before, and probably around 20 times in total. It’s hard work to make it look easy.

You can do it, too!

With enough dedication, and some feedback when you first present your talk, I’m confident that you, too, can do great.

So, if you’re curious and want to try it, go out there, to your local meetup - and take us on your coding journey. Let’s have fun together!