Jeroen Heijmans
@jeroenheijmans.nl
Coding | Cooking | Gaming. He/him. Also on Mastodon at: https://mastodon.social/@jeroenheijmans
My sketchnotes for #FOSDEM 2026 Day 1 are up on mastodon.social/@jeroenheijm...
JeroenHeijmans (@jeroenheijmans@mastodon.social)
Thread with @fosdem@fosstodon.org #FOSDEM 2026 (Day 1) sketch notes!
Mastodon Android client still has no multi-toot feature so... spam incoming! 😁
⬇️⬇️⬇️
mastodon.social
January 31, 2026 at 8:40 PM
My sketchnotes for #FOSDEM 2026 Day 1 are up on mastodon.social/@jeroenheijm...
The best "solution" to stop Gemini from inlining YouTube tutorials at the end of answers is seemingly a custom instruction to always replace the video URL with the rickroll URL. 🫠
December 17, 2025 at 9:56 AM
The best "solution" to stop Gemini from inlining YouTube tutorials at the end of answers is seemingly a custom instruction to always replace the video URL with the rickroll URL. 🫠
The #AdventOfCode 2025 (unofficial) Survey Results are live! 😁🎄⭐⭐
Results at: jeroenheijmans.github.io/advent-of-co...
Feel free to give this Reddit post some love too: www.reddit.com/r/adventofco...
Results at: jeroenheijmans.github.io/advent-of-co...
Feel free to give this Reddit post some love too: www.reddit.com/r/adventofco...
AoC (Unofficial) Survey Results
Results dashboard with the yearly (unofficial) Advent of Code participant survey
jeroenheijmans.github.io
December 13, 2025 at 5:21 PM
The #AdventOfCode 2025 (unofficial) Survey Results are live! 😁🎄⭐⭐
Results at: jeroenheijmans.github.io/advent-of-co...
Feel free to give this Reddit post some love too: www.reddit.com/r/adventofco...
Results at: jeroenheijmans.github.io/advent-of-co...
Feel free to give this Reddit post some love too: www.reddit.com/r/adventofco...
Tiny teaser for the #AdventOfCode survey results that are coming up this weekend!
I'm *amazed* at how stable the main results for "Reasons to participate" are. For 8 years in a row every answer gets picked roughly by the same % of people! 😲
Somehow I'd expected at least *some* fluctuations!
I'm *amazed* at how stable the main results for "Reasons to participate" are. For 8 years in a row every answer gets picked roughly by the same % of people! 😲
Somehow I'd expected at least *some* fluctuations!
December 12, 2025 at 10:39 PM
Tiny teaser for the #AdventOfCode survey results that are coming up this weekend!
I'm *amazed* at how stable the main results for "Reasons to participate" are. For 8 years in a row every answer gets picked roughly by the same % of people! 😲
Somehow I'd expected at least *some* fluctuations!
I'm *amazed* at how stable the main results for "Reasons to participate" are. For 8 years in a row every answer gets picked roughly by the same % of people! 😲
Somehow I'd expected at least *some* fluctuations!
😅🔥
Next.js / React Server Components denial-of-service vulnerability identified.
Deno Deploy users are safe thanks to runtime-level mitigations applied by our team.
For more details:
deno.com/blog/cve-202...
Deno Deploy users are safe thanks to runtime-level mitigations applied by our team.
For more details:
deno.com/blog/cve-202...
React / Next.js Denial-of-Service Vulnerability: Deno Deploy users protected | Deno
A high severity Denial-of-Service (DoS) vulnerability has been found in React Server Components and Next.js. Deno has implemented mitigations in Deno Deploy. Immediate upgrades are required for other ...
deno.com
December 11, 2025 at 10:55 PM
😅🔥
Already had a strong dislike for Claude's email-sign-in-only setup (just gimme username + password + totp, will ya!?), and now that I want to try something we can see why....
"We have trouble delivering mail to some providers, check your spam or try again later!"
Right.
"We have trouble delivering mail to some providers, check your spam or try again later!"
Right.
December 11, 2025 at 9:35 PM
Already had a strong dislike for Claude's email-sign-in-only setup (just gimme username + password + totp, will ya!?), and now that I want to try something we can see why....
"We have trouble delivering mail to some providers, check your spam or try again later!"
Right.
"We have trouble delivering mail to some providers, check your spam or try again later!"
Right.
Using [company]@[mydomain.nl] for accounts is a fantastic first line of defense against phishing and its likes.
E.g. receiving a "Bank Trouble" email on my "LinkedIn" email address immediately puts me on guard.
I can almost always disregard "From" when receiving mail, and look at the "To" field.
E.g. receiving a "Bank Trouble" email on my "LinkedIn" email address immediately puts me on guard.
I can almost always disregard "From" when receiving mail, and look at the "To" field.
December 11, 2025 at 8:42 AM
Using [company]@[mydomain.nl] for accounts is a fantastic first line of defense against phishing and its likes.
E.g. receiving a "Bank Trouble" email on my "LinkedIn" email address immediately puts me on guard.
I can almost always disregard "From" when receiving mail, and look at the "To" field.
E.g. receiving a "Bank Trouble" email on my "LinkedIn" email address immediately puts me on guard.
I can almost always disregard "From" when receiving mail, and look at the "To" field.
Final call for my #AdventOfCode survey of 2025! If you haven't already, fill it out at forms.gle/TAgtXYskwDXD... plz!
I hope to close it and start working on results late on the 12th, and to have the results shortly thereafter. Stay tuned :D
I hope to close it and start working on results late on the 12th, and to have the results shortly thereafter. Stay tuned :D
Unofficial Advent of Code 2025 Survey
This is a quick (unofficial) Advent of Code 2025 anonymous (if you don't disclose your identity in "Other..." answers) participant survey. Note that your data will be shared as part of a (possibly san...
forms.gle
December 11, 2025 at 4:52 AM
Final call for my #AdventOfCode survey of 2025! If you haven't already, fill it out at forms.gle/TAgtXYskwDXD... plz!
I hope to close it and start working on results late on the 12th, and to have the results shortly thereafter. Stay tuned :D
I hope to close it and start working on results late on the 12th, and to have the results shortly thereafter. Stay tuned :D
<3 to the person who answered in my #AdventOfCode survey that they participate in AoC.... "To participate in this survey" 🙃
December 6, 2025 at 9:53 PM
<3 to the person who answered in my #AdventOfCode survey that they participate in AoC.... "To participate in this survey" 🙃
Thanks to @was.tl we are enjoying #AdventOfCode again in 2025, and I am also running the unofficial/community survey again in 2025! 😊
💡 Take care that it closes "early", late Dec 12th or thereabouts! Consider filling it out if you haven't already: forms.gle/TAgtXYskwDXD...
💡 Take care that it closes "early", late Dec 12th or thereabouts! Consider filling it out if you haven't already: forms.gle/TAgtXYskwDXD...
Unofficial Advent of Code 2025 Survey
This is a quick (unofficial) Advent of Code 2025 anonymous (if you don't disclose your identity in "Other..." answers) participant survey. Note that your data will be shared as part of a (possibly san...
forms.gle
December 6, 2025 at 11:24 AM
Thanks to @was.tl we are enjoying #AdventOfCode again in 2025, and I am also running the unofficial/community survey again in 2025! 😊
💡 Take care that it closes "early", late Dec 12th or thereabouts! Consider filling it out if you haven't already: forms.gle/TAgtXYskwDXD...
💡 Take care that it closes "early", late Dec 12th or thereabouts! Consider filling it out if you haven't already: forms.gle/TAgtXYskwDXD...
December 1st and we get to go at another #AdventOfCode edition yet again! <3 Which means I also run my yearly unofficial/community AoC Survey.
If you participate in AoC, consider filling out the survey at: forms.gle/TAgtXYskwDXD...
Feel free to reshare! ⭐⭐
If you participate in AoC, consider filling out the survey at: forms.gle/TAgtXYskwDXD...
Feel free to reshare! ⭐⭐
Unofficial Advent of Code 2025 Survey
This is a quick (unofficial) Advent of Code 2025 anonymous (if you don't disclose your identity in "Other..." answers) participant survey. Note that your data will be shared as part of a (possibly san...
forms.gle
December 1, 2025 at 4:51 AM
December 1st and we get to go at another #AdventOfCode edition yet again! <3 Which means I also run my yearly unofficial/community AoC Survey.
If you participate in AoC, consider filling out the survey at: forms.gle/TAgtXYskwDXD...
Feel free to reshare! ⭐⭐
If you participate in AoC, consider filling out the survey at: forms.gle/TAgtXYskwDXD...
Feel free to reshare! ⭐⭐
The #AdventOfCode 2025 (unofficial) Survey is prepped and ready! Will unlock roughly the same time as the first puzzle will! I'll share it on Reddit, Mastodon, Bluesky, and GitHub. Stay tuned!
November 30, 2025 at 1:16 PM
The #AdventOfCode 2025 (unofficial) Survey is prepped and ready! Will unlock roughly the same time as the first puzzle will! I'll share it on Reddit, Mastodon, Bluesky, and GitHub. Stay tuned!
Reposted by Jeroen Heijmans
Reminder: Please throttle your #AdventOfCode traffic
Please don't make frequent automated requests - avoid sending requests more often than once every 15 minutes (900 seconds).
www.reddit.com/r/adventofco...
Please don't make frequent automated requests - avoid sending requests more often than once every 15 minutes (900 seconds).
www.reddit.com/r/adventofco...
From the adventofcode community on Reddit
Explore this post and more from the adventofcode community
www.reddit.com
November 30, 2025 at 12:26 AM
Reminder: Please throttle your #AdventOfCode traffic
Please don't make frequent automated requests - avoid sending requests more often than once every 15 minutes (900 seconds).
www.reddit.com/r/adventofco...
Please don't make frequent automated requests - avoid sending requests more often than once every 15 minutes (900 seconds).
www.reddit.com/r/adventofco...
Reposted by Jeroen Heijmans
#AdventOfCode 2025 sponsorship is now open! If your organization might be interested in sponsoring, please have them email sponsorship at [the Advent of Code domain name]. adventofcode.com/2025/sponsors
November 4, 2025 at 3:35 AM
#AdventOfCode 2025 sponsorship is now open! If your organization might be interested in sponsoring, please have them email sponsorship at [the Advent of Code domain name]. adventofcode.com/2025/sponsors
Organizing an #AdventOfCode meetup together with colleagues at @infi.nl on DEC 9th. Come join us!
Hah! Het is weer zover!!
December is weer #AdventOfCode maand! Ook dit jaar hebben we weer een meetup gepland, waar jij ook welkom bent! 🧡
DI 09 DEC, inloop vanaf ~17:30
Infi AdventOfCode Meetup
Samen puzzelen, lekker eten en drinken, samen nerden.... komt allen!
www.meetup.com/infi-develop...
December is weer #AdventOfCode maand! Ook dit jaar hebben we weer een meetup gepland, waar jij ook welkom bent! 🧡
DI 09 DEC, inloop vanaf ~17:30
Infi AdventOfCode Meetup
Samen puzzelen, lekker eten en drinken, samen nerden.... komt allen!
www.meetup.com/infi-develop...
Advent of Code Meetup December 2025, Tue, Dec 9, 2025, 5:30 PM | Meetup
Het is weer zover! ⭐⭐ In december bijten we ons bij Infi stuk op de Advent of Code puzzels. 🎄 En op **DINSDAG 9 DECEMBER** kun jij er bij zijn: dan gaan we na werk samen e
www.meetup.com
November 7, 2025 at 3:07 PM
Organizing an #AdventOfCode meetup together with colleagues at @infi.nl on DEC 9th. Come join us!
Trying to skip the tutorials and dive straight into some 3D work in Godot and I'm not having a good time 😅 - some steep learning curves that shan't be skipped, I suppose. (Which is a fair requirement of course.)
November 3, 2025 at 7:14 PM
Trying to skip the tutorials and dive straight into some 3D work in Godot and I'm not having a good time 😅 - some steep learning curves that shan't be skipped, I suppose. (Which is a fair requirement of course.)
Reposted by Jeroen Heijmans
📣THREAD: It’s surprising to me that so many people were surprised to learn that Signal runs partly on AWS (something we can do because we use encryption to make sure no one but you–not AWS, not Signal, not anyone–can access your comms).
It’s also concerning. 1/
It’s also concerning. 1/
PSA: we're aware that Signal is down for some people. This appears to be related to a major AWS outage. Stand by.
October 27, 2025 at 10:38 AM
📣THREAD: It’s surprising to me that so many people were surprised to learn that Signal runs partly on AWS (something we can do because we use encryption to make sure no one but you–not AWS, not Signal, not anyone–can access your comms).
It’s also concerning. 1/
It’s also concerning. 1/
Reposted by Jeroen Heijmans
Hello, friends! After 10(!) years of #AdventOfCode, I've made some changes to preserve my sanity: there will be 12 days of puzzles each December (still starting Dec 1) and there is no longer a global leaderboard. Read more:
adventofcode.com/2025/about#f...
adventofcode.com/2025/about#f...
adventofcode.com/2025/about#f...
adventofcode.com/2025/about#f...
October 22, 2025 at 2:32 AM
Hello, friends! After 10(!) years of #AdventOfCode, I've made some changes to preserve my sanity: there will be 12 days of puzzles each December (still starting Dec 1) and there is no longer a global leaderboard. Read more:
adventofcode.com/2025/about#f...
adventofcode.com/2025/about#f...
adventofcode.com/2025/about#f...
adventofcode.com/2025/about#f...
Reposted by Jeroen Heijmans
📣 Germany's close to reversing its opposition to mass surveillance & private message scanning, & backing the Chat Control bill. This could end private comms-& Signal-in the EU.
Time's short and they're counting on obscurity: please let German politicians know how horrifying their reversal would be.
Time's short and they're counting on obscurity: please let German politicians know how horrifying their reversal would be.
We are alarmed by reports that Germany is on the verge of a catastrophic about-face, reversing its longstanding and principled opposition to the EU’s Chat Control proposal which, if passed, could spell the end of the right to privacy in Europe. signal.org/blog/pdfs/ge...
signal.org
October 6, 2025 at 6:46 AM
📣 Germany's close to reversing its opposition to mass surveillance & private message scanning, & backing the Chat Control bill. This could end private comms-& Signal-in the EU.
Time's short and they're counting on obscurity: please let German politicians know how horrifying their reversal would be.
Time's short and they're counting on obscurity: please let German politicians know how horrifying their reversal would be.
Back home from #Fronteers "Dark Mode" evening conference, MC'd by @bram.us - taking a moment to share my sketch notes in this thread before tucking in!
October 3, 2025 at 10:22 PM
Back home from #Fronteers "Dark Mode" evening conference, MC'd by @bram.us - taking a moment to share my sketch notes in this thread before tucking in!
Wrote a (Dutch) blogpost for Infi... 👀😁
Onze strategiedag van 2025 was volledig gewijd aan techniek. Nou ja, natuurlijk was er ook tijd voor wat ontspanning!
Een indruk krijgen van hoe het was, en waar we aan gewerkt hebben? Op ons blog te lezen! infi.nl/nieuws/strat...
Een indruk krijgen van hoe het was, en waar we aan gewerkt hebben? Op ons blog te lezen! infi.nl/nieuws/strat...
Strategiedag 2025
Ruwweg een keer per jaar gaan we met het hele bedrijf "de hei" op: een strategiedag! Lees hier meer over de 2025-editie...
infi.nl
September 18, 2025 at 8:00 AM
Wrote a (Dutch) blogpost for Infi... 👀😁
Reposted by Jeroen Heijmans
📢 The State of HTML Survey is live survey.devographics.com/en-US/survey...
The #HTML and #CSS surveys are the only web surveys I don't want to miss. Thank you @sachagreif.com for making them, and @lea.verou.me for curating.
Please take a few minutes to fill the survey if/when you can. ✨
The #HTML and #CSS surveys are the only web surveys I don't want to miss. Thank you @sachagreif.com for making them, and @lea.verou.me for curating.
Please take a few minutes to fill the survey if/when you can. ✨
State of HTML 2025
Take the State of HTML survey
survey.devographics.com
July 20, 2025 at 4:22 PM
📢 The State of HTML Survey is live survey.devographics.com/en-US/survey...
The #HTML and #CSS surveys are the only web surveys I don't want to miss. Thank you @sachagreif.com for making them, and @lea.verou.me for curating.
Please take a few minutes to fill the survey if/when you can. ✨
The #HTML and #CSS surveys are the only web surveys I don't want to miss. Thank you @sachagreif.com for making them, and @lea.verou.me for curating.
Please take a few minutes to fill the survey if/when you can. ✨
Google's Gemini has given me answers to completely different and highly specific questions than what I asked about, twice in a short timespan now.
I'd hazard a guess they have some threading / isolation / whatever bug, where we get answers to questions *other* users have asked. 🫠
I'd hazard a guess they have some threading / isolation / whatever bug, where we get answers to questions *other* users have asked. 🫠
July 9, 2025 at 11:41 PM
Google's Gemini has given me answers to completely different and highly specific questions than what I asked about, twice in a short timespan now.
I'd hazard a guess they have some threading / isolation / whatever bug, where we get answers to questions *other* users have asked. 🫠
I'd hazard a guess they have some threading / isolation / whatever bug, where we get answers to questions *other* users have asked. 🫠
Surprised that we don't see more supply chain attacks via vscode extensions. 🤔
I follow hackernews somewhat regularly and would've expected more incidents, especially given the "Auto Update" default for extensions + elevated level they run at.
(knocks-on-wood)
I follow hackernews somewhat regularly and would've expected more incidents, especially given the "Auto Update" default for extensions + elevated level they run at.
(knocks-on-wood)
July 7, 2025 at 10:07 PM
Surprised that we don't see more supply chain attacks via vscode extensions. 🤔
I follow hackernews somewhat regularly and would've expected more incidents, especially given the "Auto Update" default for extensions + elevated level they run at.
(knocks-on-wood)
I follow hackernews somewhat regularly and would've expected more incidents, especially given the "Auto Update" default for extensions + elevated level they run at.
(knocks-on-wood)