Main logo, black
Media kit
The brand,
ready to use.
Logos, colors, type, backgrounds, photos and checked facts about Product Build Day, hands-on training in rapid product discovery. For journalists, event partners and anyone posting about it. Free to use, no need to ask.
One ZIP, 7 MB. Press questions: [email protected], answered within a business day.
Logo
Black on light, white on dark.
The wordmark comes in black and white, nothing else. Use the SVG wherever your tool accepts it, the PNG when it needs a picture.
Main logo, white
Icon
How it is built
Two lines of Inter and two slashes. The same parts make every version.
- 1PRODUCTInter Black Italic, in capitals.
- 2BUILD DAYInter Italic, regular weight, in capitals.
- 3The two slashesOn Pro and Teams the second slash turns into a slanted box with the name cut out of it.
Space and size
Give it room, and never shrink it below what the website itself uses.
Clear space
16 px, the minimum24 px, the website header48 px and up, for titlesSmallest size
Please don't
Six things that break the mark.
Recolor it
Stretch it
Tilt it
Add effects
Lose it in a photo
Product Build Day //
Retype it
City and partner lockups
For event titles, the city or partner name follows the slashes in Inter Black Italic capitals, as tall as the logo. Type a name to make one.
Colors
Five colors do most of the work.
Indigo leads. Paper and ink carry most of the text, with periwinkle for highlights and night for the dark sections. Click a swatch to copy its hex code.
Supporting colors
Shades for text and small details. Use them sparingly.
Gradients
Click one to copy its CSS.
Contrast
Measured with the WCAG 2.1 formula.12 Normal text needs 4.5:1, large text 3:1, the stricter AAA level 7:1.
AaWhite on indigo
12.8:1
AAA, any size
AaWhite on night
18.4:1
AAA, any size
AaInk on paper
18.2:1
AAA, any size
AaIndigo on paper
11.7:1
AAA, any size
AaLavender on night
10.9:1
AAA, any size
AaSoft violet on indigo
4.2:1
Large text only
AaWhite on periwinkle
4.1:1
Large text only
AaPeriwinkle on paper
3.8:1
Large text only
Type
One typeface: Inter.
Inter Black Italic for the logo and titles, Inter Regular for text. The website adds the weights in between. Free on Google Fonts.
Aa
Inter Black Italic, weight 900
Who does what
Each style has one job. The specs come from the website and the Canva templates.
Logo and titles in graphics
Inter Black Italic, 900. Capitals, tight tracking, line height 0.9.
One day in.
One decision out.
Headlines on the website
Inter ExtraBold, 800. Sentence case, tracking -3.5%, line height 0.96. The second sentence can turn periwinkle.
One day in.
One decision out.
Lead
Inter Medium, 500. 18 to 26 px, line height 1.4.
Find out if your idea is worth a quarter, in a day. No dev team, no code.
Body text
Inter Regular, 400. 17 to 21 px, line height 1.5, body grey on paper.
Everyone can build anything now. Almost nobody stops to ask whether it is worth building. Here you start at the other end: the cheapest test that tells you whether anyone wants it.
Labels
Inter SemiBold, 600. 13 px, capitals, tracking +14%, indigo. On the website, labels are the only text in capitals.
The evening
Sublines in graphics
Inter Italic, 400. Soft violet on indigo, or white at half opacity on the aurora.
No code. AI does the typing.
Numbers
Inter ExtraBold, 800, with tabular figures so columns line up.
80 people.
80 prototypes.
One accent
Georgia Italic, used sparingly for a quote, like the manifesto line in the website footer.
“An idea that cannot survive a day is not worth a quarter.”
Sizes on the website
Headlines grow with the screen. Each bar runs from the phone size to the widest desktop size, in pixels.
Hero headline44 to 124 px
Section headline40 to 104 px
Big numbers36 to 66 px
Lead18 to 26 px
Body text17 to 21 px
Labels13 px
Backgrounds
The aurora is the signature.
A soft blur of blue and deep night with a warm glow in one corner, under a light film grain. It sits behind posts, slides, certificates and the homepage. Every background comes in 16:9 for slides, 4:5 for feed posts and 9:16 for stories, as full-quality JPG.
CSS for developers
:root {
--indigo: #1800AD;
--periwinkle: #5170FF;
--night: #140E33;
--paper: #F7F5F0;
--ink: #0A0A0A;
--lavender: #B9C4FF;
--soft-violet: #9487E7;
--font: 'Inter', sans-serif;
}/* Aurora, as on productbuildday.com. Put it on an oversized layer (inset: -15%). */
.aurora-night {
background-color: #140E33;
background-image:
radial-gradient(40% 50% at 20% 28%, rgba(81,112,255,.85), transparent 68%),
radial-gradient(32% 40% at 68% 84%, rgba(255,170,110,.42), transparent 70%),
radial-gradient(42% 50% at 28% 82%, rgba(70,46,150,.78), transparent 72%),
radial-gradient(30% 38% at 52% 50%, rgba(176,201,255,.32), transparent 75%);
filter: blur(156px);
}
/* Film grain, laid over any surface */
.grain {
position: absolute; inset: 0; pointer-events: none;
mix-blend-mode: overlay; opacity: .55; background-size: 170px 170px;
background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='160' height='160'><filter id='n'><feTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2' stitchTiles='stitch'/><feColorMatrix type='saturate' values='0'/></filter><rect width='100%25' height='100%25' filter='url(%23n)'/></svg>");
}In use
Five layouts that repeat.
Real files from recent events, with the recipe for each one.
Photos
Photos from the rooms.
Eight shots from Warsaw, Athens and the September evenings. The arrow gets you the full size.
Facts
The numbers, checked on 1 October 2026.
Each number links to its source at the bottom of the page. If you quote one, please quote the date with it.
6
events in six countries: Poland, Greece, the Netherlands, Denmark, Sweden and Germany7
131
people have built with us: 123 at the six events, 8 on a private day for Ionian Technologies1,2,3,4
<50%
of applicants get a seat. Every event is curated, and I read each application myself.5
80
prototypes in four evenings, Amsterdam to Berlin, 14 to 17 September1
30/30
Trustpilot reviews give five stars. TrustScore 4.7, rated Excellent.6
Read the reviews on Trustpilot55%
of the people in the September rooms were senior, lead, head, director or founder1
10 yrs
median work experience in those rooms1
What it is
Rapid product discovery, with the emphasis on usability and on validating the idea before anyone invests more.
- 01Design the smartest, cheapest testThe one test that shows whether the idea holds, before it costs a quarter.
- 02Build it with AIA working app, no code needed. AI does the typing.
- 03Test its usabilitySynthetic users show where people get stuck, so it gets fixed before real users see it.
- 04Go or no-goA clear call on further investment, pitched to the people who decide.
Who was in the room, September 2026
Share of the 80 people across Amsterdam, Copenhagen, Stockholm and Berlin, rounded. Bars are scaled to the largest group.1
People who built, per event
21
22
80
Warsaw4 July 2026Athens11 July 2026September tour4 cities, 4 evenings
The September bar covers Amsterdam, Copenhagen, Stockholm and Berlin, in one week.1,2,3
The six events
Oldest first.7
4 July 2026
Warsaw
Imaguru Startup HUB
21 builders, 21 apps, sold out2
Case study →11 July 2026
Athens
Basil & Elise Goulandris Foundation
22 builders, 6 apps, sold out3
Case study →14 September 2026
Amsterdam
House of Watt
September tour, evening 1
Tour recap →15 September 2026
Copenhagen
Famly
September tour, evening 2
Tour recap →16 September 2026
Stockholm
Embassy House
September tour, evening 3
Tour recap →17 September 2026
Berlin
Techtelmechtel
September tour, evening 4
Tour recap →Coming up
Confirmed dates as of 1 October 2026.
7 October 2026
Bucharest
Session at How to Web7
Details →26 November 2026
Berlin
Pro training, curated group of 128
Details →Three formats
The same method in three formats.
Free evening
- Three hours, in person, in English
- Curated: you apply, and I pick the room
- One shared challenge, from the cheapest test to a live pitch
One-day training
- Next date: Berlin, 26 November 2026
- Curated group of 12
- Build it. Test it. Pitch it.
Private day
- Inside your company
- Up to 20 people
- Your riskiest bets, with a go or no-go on each
Tools
Lovable sponsors the build tool. Uxia sponsors the synthetic user testing.
Hosts so far
Where the builders work
People who built with us in 2026 work at these companies.8
Individual attendance does not imply any endorsement or affiliation.
Wording
Copy it as it is.
Descriptions in three lengths and the rules for the name.
Product Build Day is hands-on training in rapid product discovery: design the smartest, cheapest test for an idea, build the app that runs it with AI, check its usability and leave with a go or no-go on further investment.
Product Build Day trains product managers and designers in rapid product discovery. In one day they design the smartest, cheapest test for an idea, build a working app with AI tools without writing code, and check its usability with synthetic users. The emphasis is on validating the idea before anyone invests more: the day ends with a go or no-go on further investment, pitched to the people who decide. It runs as free community evenings, a one-day Pro training and private Teams days inside companies.
Product Build Day trains product managers and designers in rapid product discovery. In one day they design the smartest, cheapest test for an idea, build a working app with AI tools without writing code, and check its usability with synthetic users. The emphasis is on validating the idea before anyone invests more: the day ends with a go or no-go on further investment, pitched to the people who decide. It runs as free community evenings, a one-day Pro training and private Teams days inside companies.
Marcin Klimaszewski, former Head of UX at Sanoma Learning, founded it in 2026. It has run six events, in Warsaw, Athens, Amsterdam, Copenhagen, Stockholm and Berlin, plus a private day for a company in Thessaloniki, and 131 people have built with it so far. Every event is curated, and fewer than half of the applicants get a seat. Lovable sponsors the build tool and Uxia the synthetic user testing. The whole method is free to read in the Facilitator's Playbook, under a Creative Commons license.
The name and the lines
Write it the way the website does.
- The name
- Product Build Day. Three words, each with a capital.
- The category
- Rapid product discovery, with the emphasis on usability and on validating the idea.
- With slashes
- For formats and event titles:
Product Build Day // ProProduct Build Day // TeamsProduct Build Day // Berlin - Main line
- One day in. One decision out.
- Training line
- Build it. Test it. Pitch it.
- Manifesto
- An idea that cannot survive a day is not worth a quarter.
- Language
- Every event runs in English, in person.
Founder
Marcin Klimaszewski
Founder of Product Build Day. He runs every edition himself.
- 15years in product and UX9
- 100+workshops across Europe9
- 2ndat TechArena Sweden 2026, entered solo against 90+ people9
- 35people in the team he hired as Head of UX at Sanoma Learning, across five countries9
Marcin Klimaszewski founded Product Build Day, where he trains product managers, product owners and designers to take an idea from assumption to a decision in one day: build it with AI, test it, then get a go or no-go from the people who hold the budget. 130+ people in six countries have built with him.
Marcin Klimaszewski founded Product Build Day because building got cheap and deciding got hard. He trains product managers, product owners and designers to take an idea to a decision in one day: define the challenge and decide what metric would kill it, build a working app with AI, check its usability with synthetic users, design the cheapest test with real customers, then get a go or no-go from the people who hold the budget. 130+ people in six countries have built with him. With the same method he came second at TechArena 2026 in Stockholm, solo, against more than 90 people. He spoke on the main stage of How to Web 2026, is a Lovable Expert Partner.
License and contact
Free to use. Send me the link.
- Use anything here in articles, posts, slides and event pages, without asking first.
- Quote the numbers together with their date.
- Call it rapid product discovery.
- Don't recolor, stretch or redraw the logo.
Questions, interviews, or a photo you can't find here: write to [email protected] and I answer within a business day.
Last updated 1 October 2026.
Sources
- September tour case study, productbuildday.com. 80 people and 80 prototypes, the role split, 55% senior or above, 10 years median experience, the tools on the night.
- Warsaw case study, productbuildday.com. 21 builders, 21 apps, sold out.
- Athens case study, productbuildday.com. 22 builders, 6 apps from 5 teams, sold out.
- Ionian Technologies case study, productbuildday.com. A private day in Thessaloniki, May 2026: 8 builders in pairs, 4 challenges.
- Product Build Day application and selection records, 1 October 2026. Fewer than half of applicants were offered a seat.
- Product Build Day on Trustpilot. 30 reviews, all five stars, TrustScore 4.7, read 1 October 2026.
- Events, productbuildday.com. Every event with its city and date.
- Pro training, Berlin, productbuildday.com. Date, curated group of 12, and the companies the 2026 builders work at.
- About Marcin, productbuildday.com. Years in product, workshops, TechArena, Sanoma Learning.
- Lovable partner directory. Listed as Expert Partner.
- Inter on Google Fonts and its license file. SIL Open Font License 1.1, by Rasmus Andersson.
- W3C, Understanding contrast (minimum) and contrast (enhanced). Ratios on this page are computed with the WCAG 2.1 formula.