Niels Leenheer
@html5test.com
CTO of Salonhub. Creator of http://html5test.com, writes at http://nielsleenheer.com, team @FronteersConf, Google Developers Expert, Invite me to speak at your event.
This year’s FFConf is shaping up to be genuinely unmissable. So …um, you know …don’t miss it: https://2026.ffconf.org/ I’ll see you there! 🔗 https://adactio.com/notes/22807
Two upcoming conferences this November where I will give a talk about how I created CCS DOOM: November 13th - FFConf 🇬🇧 Brighton 2026.ffconf.org November 16th - Halfstack 🇦🇹 HalfStack halfstackconf.com/vienna Both are amazing conferences and have a lovely community. Tickets are still for sale!
Mood for this morning: The Skinner Brothers with the Rampage EP - perfect to drown out intrusive thoughts about the state of the world with a violent sonic mix of punk, ska and drum and bass.
Mood for today… this is my go to record when I just want to relax.
Can't believe that in less than 4 weeks I will be in Brighton to give a talk about how I build CSS DOOM at @ffconf.org Despite being on my bucket list to attend and speak for at least 10 years, I never managed to visit. But this year I will do both.✨ 🎟️ Tickets are still for sale: 2026.ffconf.org
FFConf 🌟 UK web conference since 2009
FFConf - the UK's best JavaScript and Web conference in Brighton.
2026.ffconf.org
Vienna next month. 👀 HalfStack is a day of people showing what they’ve built, trying things that seemed like a good idea, meeting curious web people, and hanging around afterwards. Plus the JS Pub Quiz and karaoke. 🎤 📅 16 November 2026 📍 Ankersaal, Vienna 🎟️ halfstackconf.com/vienna/tickets
Okay… who knows a good alternative to Deno Deploy that isn’t Cloudflare. We use Cloudflare for one of our products and need something worker/deno-like on a completely separate infrastructure.
Whew, we're still reeling from Fronteers: Dark Mode this past friday! We brought developers from multiple countries together to celebrate front-end and human connection. It was super "gezellig"! Thank you everyone for helping us make this event happen, thank you for supporting Fronteers!
Arrived early in Dordrecht. Tomorrow Fronteers Dark Mode, but first I have an appointment at the regional archives for research. A lot is scanned and online, but today I’ll be handling actual notary acts from around 1600.
After careful consideration and a look at where the industry is spending it's funding we've decided to pivot #FFConf in a "new" direction. I present to you: ffconf.ai Please share with bots and humans alike.
FFConf.ai
The web conference, now with 100% less you. Agent-first, human-optional, ice cream not included in the Enterprise tier.
ffconf.ai
Chaos in my office as I am testing the tech setup for the @fronteers.bsky.social Dark Mode conference.
HalfStack isn’t just the presentations. It’s the people you meet, the things you end up talking about afterwards, the JS pub quiz, and a bit of karaoke. We’re back in Vienna on 16 November. Come spend the day with us. ❤️ 📍 Ankersaal, Vienna 🎟️ halfstackconf.com/vienna/tickets #HalfStackVienna
And this is what I've been spending my evenings on lately. A decoder for receipt printer protocols. You can take the bytes that get send to a receipt printer and inspect the commands that are inside of it. And... actually see a render of the receipt. Only useful for a hand full of people. And me.
⏰ Last call for Fronteers Dark Mode 2026! Ticket sales close tomorrow, Saturday at midnight, and there are just 13 seats left. So if you’ve been thinking about joining us in Dordrecht next Friday, this really is your last chance. 🌑✨ 🎟️ www.fronteersconf.org We’d love to see you there! ❤️
For 15 years I've been obsessed with receipt printers and the protocols that they speak. I created an open-source encoder that can run in the browser can create receipts and send them to the printer. That turned into a whole project that is now used by dozens of products: point-of-sale.dev
Fronteers Dark Mode conference is next week! Monday I'll send badges to the printer... which means if you want a proper badge... sign up now! We've got a handful of tickets left and they are only €100 for an evening of front-end talks by some amazing speakers. www.fronteersconf.org
Fronteers Dark Mode, Friday, October 2nd, Dordrecht
Join us at Cinema de Witt in Dordrecht for our after work conference.
fronteersconf.org
Two weeks from now Fronteers Dark Mode will happen in Dordrecht in The Netherlands. There are still a few tickets left. Be quick ⚠️ Join us for an afternoon and evening of great talks. With a spectacular line up: @anjana.dev, @tunetheweb.com, @cydstumpel.nl, @csswizardry.com and @heydonworks.com
It is weird how the brain works. I am a public speaker. I organise conferences. I still get shy talking to other speakers. Every single time it is a threshold that I have to cross. Then I remember that I, as a speaker, would love to have a chat. So I do, and made some lovely friends along the way.
you really should and I need to do it more too ohhelloana.blog/tell-the-spe...
I'm down one of the rabbit holes again. I *just* wanted to print receipts on a Star TSP100 printer. Initial problem: unlike other printers, it does not support text, only graphics. And my receipt printing library only supports rendering to text based ESC/POS and StarPRNT...
At the train station in Freiburg after a very lovely @smashingconf.com, waiting on the night train back home. Been lovely talking to all the other attendees, speakers and organisers. See you next year!
Hello Freiburg 👋🏻 Anybody know a good place to have some lunch and where I can work on my talk a bit for tonight?
Over the years I have brought some really weird things through airport security. I’ve set off the alarms once - they closed down the lane and started shouting in panic because it looked really serious on the scanners. But never a vintage oscilloscope. Until today. Freiburg, here we come!
Flying tomorrow to Freiburg for @smashingconf.com, now at my hotel at Schiphol editing slides for a small 10 minute Jam Session talk. Was so swamped with work that I forgot to send @charismagic.studio what I wanted to talk about, so she just picked a title and I am now building slides to match 😅
"Oscilloscopes & Other Bad Ideas" I've been so swamped in work that I completely forgot that I am going to give a talk at the @smashingconf.com Jam Session next monday. But with a title like that I already know it's going to be good. smashingconf.com/freiburg-202...
Jam Session — Freiburg in Germany, September 7–10.
The night before the conference kicks off, we’re hosting Jam Session with our dear friends from Reservix, with a few snacks, drinks and micro talks from your fellow attendees! We hope you’ll join us t...
smashingconf.com
Without saying your age, what is your favorite movie that came out when you were 20 years old? This one was difficult to pick. There were a couple of great ones that year. But this one wins.
Brad Pitt in 12 Monkeys - Intense Scene
ALT: Brad Pitt in 12 Monkeys - Intense Scene
static.klipy.com
Without saying your age, what is your favorite movie that came out when you were 20 years old? This is harder than it looks. Pretty much all my favourite films came out AROUND when I was 20 but not actually IN that year. Weird that all the best films in history came out exactly when I was that age
I didn’t think I’d ever agree with DHH, but he is totally right. Linux is infiltrated by absolute maniacs. Anyone still using any of DHH’s products should be taking a very close look at themselves.
re: omarchy trying to create parallel infra to subvert the linux community and kick trans/female/black people out i know some people think that sounds crazy but DHH literally is doing a podcast tour saying that is exactly what he's doing lol
Introduce yourself with 10 acts you’ve seen live: Marillion Fish Egdon Heath Focus Micheal Jackson Björk Massive Attack Portishead The Big Push Ren <- earlier today And so many more. I could fill the list with just Fish, saw him at least a twenty times.
Introduce yourself with 10 acts you've seen live: Less Than Jake Frank Turner Bob Dylan Hans Zimmer Reel Big Fish Lemon Jelly Metallica Green Day Public Service Broadcasting & many swing dance bands
WebMCP has been an interesting journey for me. Initially not seeing the point, even sceptical it should even be part of the web. Agents can use HTML, just like everybody else, right?