Demo Why Not What
A Recipe for Great Engineering Demos
Intro
This year at Square we started shipping aggressively. Powered by a completed migration, new feature roadmaps, and AI adoption, we shifted into a build, demo, iterate, ship cycle. My team was showing our work to other engineers all the way up to the C-suite. To help us stand out I put together a short framework of how to make demos great, especially while shipping fast and showing progressive improvement.
This is that framework.
Why Not What
The "what" in a demo is obvious, it's on the screen. The audience can see the buttons and the flow of the UI. What they can't see is why it matters. Stories ground the features we build by making an example of their usefulness. Without a story, the audience is left to guess the value.
Fine vs. Great
Fine Demo: What was built
"We added a modifier button to the order screen."
Great Demo: The problem it solves
"Baristas needed a faster way to customize drinks during rush hour without slowing the line."
Fine Demo: Walks through features
"First you tap here, then select the size, then add modifiers from this menu..."
Great Demo: Tells a customer story
"A regular walks in and orders their usual. The barista pulls up their history and the order is ready in two taps."
Fine Demo: Audience evaluates the work
"We implemented item search using the new API and added caching."
Great Demo: Audience imagines the user whose day got easier
"Now when the line is out the door, the barista isn't fumbling through menus, they're making drinks."
Lead With a Story
Before showing anything, answer these four questions from the user's perspective:
Who are you? Give the audience a person to root for.
What are you trying to do? Set up the job to be done.
What was painful before? Make the problem known.
What's different now? Show the contrast.
Demo Recipe
Follow this structure to build a compelling narrative!
Open with a one-sentence persona + goal
"A seller at a busy counter needs to get someone checked out fast."
Name the pain in one sentence
"Before, this meant digging through three menus to find the right option, which backed up the line."
Show the happy path first One clean flow. No detours, no edge cases. Just the thing that proves the value.
Call out the moment of value Don't make the audience guess. Say it:
"This is the part that used to take 30 seconds. Now it's two taps."
Close with the outcome Time saved. Fewer errors. Clearer decisions. Happier customers. Name the win.
Save build details for the end Technical deep-dives are great for people who want them. Offer them as a follow-up, not the main event.
Make It Stick
Critical
Visibility Matters - Introduce yourself and your team at the start, call out contributors by name when showing their work, and share credit generously. Demos are a team effort!
Keep it short - A tight demo is 1–3 minutes, not 10.
Trust your instincts - If it feels too short, it's probably right.
Rehearse once - Even one dry run catches awkward transitions and filler words.
One takeaway - What's the single sentence the audience should walk away with? Know it before you start.
Polish
Clean your environment - No "Test User 69." Realistic data makes it believable.
Consider a backup - Live is better, but a 30-second video or a few screenshots can save the moment.
Handle questions at the end - "I'll cover that at the end" keeps the flow intact. Answering mid-demo often derails the story.
Credibility
- Own the gaps - Call out what is missing and what's coming next.
Common Traps
Don't apologize for what's not done yet
❌ "Sorry, this part isn't quite finished but…"
✅ "This is in progress - here's what's coming next."
Don't detour into bugs or edge cases
❌ "Now if you do this weird thing, it breaks but…"
✅ Save edge cases for Q&A unless they're critical to the story.
Don't narrate clicks
❌ "And then I click here, and then I click here…"
✅ "I'll add the modifier…" (while clicking)
Handling Q&A
Repeat the question - Ensures everyone heard it and gives you time to think.
Bridge back to the story - "That's a great question about [XYZ]. Remember our bartender…"
Defer deep dives - "That's a great technical question, let's sync after."
Make space for multiple voices - Take the lead and go through the queue of people asking questions. Take one or two from an individual before moving on.
Know Your Audience
Leadership - Focus on outcomes and metrics. "This saves $2 or 2 minutes per transaction."
Engineers - Show the happy path, then offer technical deep-dive. "Want to see how we handle error handling?"
Customers - Emphasize ease and reliability. "You'll never lose a sale again!"
