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jflessau.bsky.social
Jan
@jflessau.bsky.social
73 followers 99 following 77 posts
Software dev for health care products by day, side project hoarder by night.

🦀 rust | 🎾 padel | 🎲 dnd | 🖨️ 3d printing

📍 Hamburg, Germany

Website: https://jflessau.com
GitHub: https://github.com/jflessau
Mastodon: https://hachyderm.io/@jflessau
Posts Replies Media Videos
jflessau.bsky.social
I can see myself making this mistake at some point.

#dev #bash

qouteall.github.io/qouteall-blo...
A screenshot showing a bulletpoint of a blogpost with the text: "If DIR is unset, rm -rf $DIR/ becomes rm -rf /. Using set -u can make bash error when encountering unset variable."
August 16, 2025 at 10:58 PM
jflessau.bsky.social
Rooting for this little fella to escape from my monitor before dying. Any tips?
July 21, 2025 at 1:37 PM
jflessau.bsky.social
Used a text-to-image model, then an image-to-3d model. Cleaned, rigged, and painted it in Blender. Feeling a bit conflicted, but I see no other way to make my game happen alongside a full-time job without AI. Thoughts?

#gamedev #ai #bevy
July 19, 2025 at 11:33 AM
jflessau.bsky.social
Using #bevy and #blender to create my first 3D video game.

#gamedev
July 5, 2025 at 10:50 AM
jflessau.bsky.social
A few months ago, my application with the Fuel Registry of the German Federal Cartel Office was approved. With access to the gasoline and diesel prices they provide for all of Germany, I'm now building a small web app.

#webdev #CivicTech #buildinpublic
A screenshot of a web app in mobile portrait mode. The navigation bar at the top shows the title "McSprit," followed by an icon of a fuel nozzle and a search input field. Below the navigation bar is another bar displaying the selected location (Hamburg, zip code 20354, Germany in this case), the selected fuel type (Super E10), and the distance (5 km) for the radius search. Below that is a 2x2 grid showing the number of gas stations (12), the average price (1.59 €), the minimum price (1.45 €), and the maximum price (1.72 €). Below that is the headline "Tankstellen" ("gas stations" in English) and a list of gas stations with their name, zip code, current price, and distance. The list is filled with mock data (gas station 1, gas station 2, etc.).
May 24, 2025 at 8:32 AM
jflessau.bsky.social
A 3D printable frame for an e-ink display and a public website to control its content.

I'll let the internet decide what I see next.

What could go wrong?

Control the frame here: inkday.jflessau.com

Or set up your own: github.com/jflessau/ink...

#3dprint #diy #webdev
An e-ink display in a 3D-printed frame on a desk. It shows a turtle on the display.
May 17, 2025 at 4:31 PM
jflessau.bsky.social
Google: Material 3 Expressive is the most researched update to Google’s design system, ever.

HN:
Hacker News screenshot of the post about Material 3 Expressive. First sentence of the first comment is highlighted: „How did these clowns manage to make my mouse cursor laggy?“ Rest of the comment: „It is incomprehensible for me to live in such a big bubble with such a big paycheck and then spend zero brainpower on systems without graphics acceleration. This is extremely bad engineering and these engineers should be called out for it. It takes a special kind of person to deliver this and be proud of it.“ Info about the posting itself: Title: Material 3 Expressive Website: design.google 180 points Author: meetpateltech 9 hours ago 292 comments
May 16, 2025 at 3:48 PM
jflessau.bsky.social
Trying out agentic editing in the #Zed editor. It's mesmerizing to watch it create and edit files 🌀

Building a PWA to track expenses collaboratively. For this little side project, it's working surprisingly well.

#webdev #solidjs #buildinpublic
A website displayed in portrait mode. The navigation bar at the top includes a back button on the left, the username "jflessau" in the center, and a settings icon (cog) on the right. Below, the headline reads "Road Trip." Underneath are two buttons: "Copy Invite Code" and "Settle Up." Below these is a list of members, currently showing just one: "Joana Doe." Further down is a history of expenses and transactions. Transactions indicate who sent money to whom. Expenses have a title (e.g., "Gasoline"), a user count showing how many people the expense was split between, and an icon indicating the split type (split evenly or custom amounts per user). At the bottom of the page is a button to delete the tracking project.
May 12, 2025 at 12:13 PM
jflessau.bsky.social
Made this 3D printable base for #dnd minis that projects a field of view cone with an adjustable angle.

STL files and some more pictures are available here:

jflessau.com/projects/bea...

#3dprint #3d #rpg
May 7, 2025 at 9:32 PM
jflessau.bsky.social
Built a thing that creates 1-2 minute audio digests from hashtag posts. What do you think?

#buildinpublic

Includes posts from:
jkemppainen.com - vehicle combat game
monfang.bsky.social - outreach strategy
chromatic-ai.bsky.social - PRAY app revenue
indieceo.bsky.social - open-source licensing
March 13, 2025 at 9:08 PM
jflessau.bsky.social
Inspired by hnup.date. I loved the site, but when it went down for a while, I created this replacement. Now that hnup.date is back, it's definitely worth checking out!

I used activepieces.com as my self-hosted workflow automation tool:
A screenshot of connected workflow steps. Some steps are omitted, such as the one querying the Hacker News API. The steps shown work with the text data retrieved from the API: 1. Ask ChatGPT for a summary. 2. Use custom JavaScript to calculate the number of characters in the summary (TTS is expensive, so we're only sending texts below 20k characters to the TTS API). 3. If-else condition: A) text is shorter than 20k characters, B) text is longer. 4. Text-to-speech (branch A of the if-else). 5. Send email (also branch A of the if-else). Branch B is never used.
March 9, 2025 at 10:25 PM
jflessau.bsky.social
Tried a drag-and-drop workflow tool and built an #automation that grabs the top X #HackerNews stories with their top Y comments. It uses AI to summarize and convert them into a 1-3 minute audio digest sent to my inbox twice a day. Loving it!
March 9, 2025 at 10:25 PM
jflessau.bsky.social
Just rediscovered my Pixabay account and saw that my vector graphics have been downloaded 5 million times! 🎉

Reverse image search showed that they're all over the internet. Made my day! :)
Screenshot of pixabay account statistics: 13k likes, 8 million views, 5 million downloads
March 7, 2025 at 8:18 AM
jflessau.bsky.social
Wanted a #postgres fan shirt, so I made this using #ai and #affinityphoto.

Printed shirt will arrive in a few days.
Postgres Ultras fan shirt design featuring a muscular elephant framed from head to shoulders, with the text "POSTGRES ULTRAS" below it.
February 18, 2025 at 10:15 PM
jflessau.bsky.social
My take on a habit tracker web app:

- 👤 No login required
- 🔌 Works offline
- 📁 Import & export data
- 📄 MIT licensed

Built with #rust and #leptos.

Demo: ritmo.jflessau.com
Repo: github.com/jflessau/ritmo

#webdev #buildInpublic #rustlang
February 15, 2025 at 6:09 PM
jflessau.bsky.social
Postgres is indeed a lot faster. Tested this a while back and I‘m unsure if surreal will catch up for analytical queries with a lot of aggregation. It‘s also quite easy to write slow queries by using nested relations with where clauses like 'user->posts->post[where createdAt < time::now()]<-likes…'
Postgres: populate table 10 s count all users 38 ms get ten users with most coins 30 ms sum of all coins from all users 25 ms Surreal: populate table 65 s count all users 6 s get ten users with most coins 8 s sum of all coins from all users 8 s
January 30, 2025 at 10:35 PM
jflessau.bsky.social
For some inspiration: Here's the top of my 'I'll try that someday' list :)
A bulletpoint list. Here are all the points on it: • Browser extension to read text in a user-selectable voice. • Availability zones for everything from take-away food and car sharing to grocery deliveries, with notification emails if something new pops up in your area. • (Web) app for splitting expenses. •Pen & Paper Character Tinder: find the perfect match for your next campaign/one-shot. • Some fun GitHub actions, like ordering food via Uber on a new release. • Control Philips Hue lights with a VSC extension. • GitHub contribution widget for Android (the only one I know of is kind of ugly). • Meow Meow Beans app (in case you like the series "Community"). • (Web) app for creating/playing text RPGs.
January 7, 2025 at 12:42 AM
jflessau.bsky.social
Populated a table with 1 million rows in both #Postgres and #SurrealDB and ran queries.
Postgres is significantly faster.
Two tables, one for Postgres, one for Surreal. Postgres: populate table 10 s count all users 38 ms get ten users with most coins 30 ms sum of all coins from all users 25 ms Surreal: populate table 65 s count all users 6 s get ten users with most coins 8 s sum of all coins from all users 8 s
January 4, 2025 at 2:25 PM
jflessau.bsky.social
I'm building a Postgres desktop GUI in Rust using the gpui crate (the framework used to create the Zed editor).

These are the humble beginnings, and I'm having the time of my life with this project :)

#postgres #rustlang #zed
December 16, 2024 at 9:19 PM
jflessau.bsky.social
I’ve created a web app that detects voice activity and inserts canned laughter in between.

I call it Sitcom as a Service.

Check out the demo: canned-laughter.jflessau.com

Hint: doesn’t work in Safari

#webdev #svelte #rust #rustlang
December 15, 2024 at 10:58 AM
jflessau.bsky.social
I created a web app for chatting with people on the same public transport vehicle.

It automatically connects users with similar location, speed, and direction of travel. No login required.

Repo: github.com/jflessau/cat...
Demo: catenary.jflessau.com

#rust #leptos #webdev
December 13, 2024 at 11:30 PM
jflessau.bsky.social
Created this in #blender to generate 3D-printable drawer inserts for organizing items.

If you’d like to generate some for yourself, you can do so with just a few clicks:

github.com/jflessau/dra...

#3dprinting #blender3d
December 13, 2024 at 11:26 PM
jflessau.bsky.social
Made a multiplayer BS bingo game using #rust and #svelte.

Game: bingo.jflessau.com
Repo: github.com/jflessau/bs-...
December 13, 2024 at 11:23 PM