Joe Walnes's Avatar

Joe Walnes

@waln.es

Building new stuff at Stripe. Previously: Apple, Google, Thoughtworks, trading, founder. Open source: websocketd, xstream, hamcrest, and others… github.com/joewalnes linkedin.com/in/joewalnes x.com/joewalnes

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16.11.2024
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Latest posts by Joe Walnes @waln.es

I've cracked it! A foolproof unbreakable human vs AI captcha test.

---

Are you human?

◯ Yes - I'm definitely human
◯ Yes — I'm definitely human

04.02.2026 22:57 👍 0 🔁 0 💬 0 📌 0
From the LV426 community on Reddit: Build your own LEGO Eyeball Alien! (Cat sold separately) Explore this post and more from the LV426 community

Cute LEGO eyeball creature thingy

www.reddit.com/r/LV426/comm...

13.09.2025 07:54 👍 3 🔁 0 💬 0 📌 0

Just setup plausible. Took less than a minute to get up and running. Beautiful ❤️

20.08.2025 03:38 👍 2 🔁 0 💬 0 📌 0

What web analytics tools y’all using these days?

Looking for:
- lightweight (fast loading)
- privacy centric: no creepiness, no ad tracking, just give me high level insights,
- GDPR friendly
- simple dashboards
- alerts of spikes
- not too expensive to run on many sites (doesn’t have to be free)

20.08.2025 01:34 👍 2 🔁 1 💬 3 📌 1
Preview
TeenyTiny AI Replace your slow, expensive, large language models with instantaneous, free, tiny language models. OpenAI API compatible. Probably no down side.

teenytiny.ai

Its retro

19.08.2025 19:19 👍 5 🔁 1 💬 0 📌 1

SaaS builders: which libraries/frameworks are you using to interact with LLMs?

How are you dealing with LLM costs? Is it a problem?

13.07.2025 16:50 👍 2 🔁 0 💬 0 📌 0
Post image

The Commodore 64 is back!

commodore.net

13.07.2025 16:46 👍 4 🔁 1 💬 0 📌 0

A car commute is the perfect amount of time to build and ship ideas. I just gotta keep my eyes on the road.

Looking for a fully voice controlled AI coding tool, ideally works on phone.

What tools can help me do this? Or do I need to vibe code it myself (while not driving!)

30.06.2025 01:49 👍 1 🔁 0 💬 2 📌 0
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Community Communications, Product/Developer Help increase the GDP of the internet as part of our Communications team.

Like talking about AI and the future of business? Like creating content and building community?

Come help us!

stripe.com/jobs/listing...

27.06.2025 15:11 👍 1 🔁 0 💬 0 📌 0

The second best:

"Test first! Before adding functionality or fixing anything, write a test that can reproduce the failing state first. Prefer to build high level integration tests that actually surface the issue in a realistic environment. Be confident it works before stopping."

24.06.2025 17:15 👍 1 🔁 0 💬 0 📌 0

The best line I've ever added to CLAUDE.md:

"Before each commit, reflect on the lessons we've learned together and update CLAUDE.md for future use. Focus on generic patterns and techniques, not specifics of a single feature."

24.06.2025 17:08 👍 1 🔁 0 💬 1 📌 0

Love this so much!

24.05.2025 17:42 👍 3 🔁 0 💬 0 📌 0
A screenshot of Compiler Explorer showing an "AI Explain this" view. The source code is: 

bool isspc(char c) { 
    return c == '\n' || c == '\r' || c == '\t' || c == ' ';
}

The asm is:
isspc(char):
        mov     ecx, edi
        cmp     cl, 33
        setb    dl
        movabs  rax, 4294977024
        shr     rax, cl
        and     al, dl
        ret

Below is a "Claude Explain" window with:

The function isspc(char) is compiled to an efficient bit manipulation technique to check for whitespace characters. Let's break down the assembly instructions:

mov ecx, edi

Copies the input character from the edi register (first function argument) to ecx
cl will contain the lowest 8 bits (the character)
cmp cl, 33

Compares the character against decimal 33
This is a preliminary check to quickly filter out non-whitespace characters
setb dl

Sets the dl register to 1 if the character is below 33 (space, tab, newline, etc.)
Uses a conditional set instruction
movabs rax, 4294977024

Loads a pre-computed 64-bit constant
This constant represents a bit mask for whitespace detection
shr rax, cl

Shifts the bit mask right by the character's value
This dynamically positions the mask based on the input character
and al, dl

Performs a bitwise AND between the shifted mask and the previous condition
Produces the final boolean result in al
ret

Returns the result (0 or 1) in al
This implementation is a highly optimized branchless method for checking whitespace characters, using bit manipulation instead of multiple comparisons. It avoids conditional jumps, which can be slower on modern CPUs.

The code checks for space (' '), newline ('\n'), carriage return ('\r'), and tab ('\t') in a single, efficient operation.

A screenshot of Compiler Explorer showing an "AI Explain this" view. The source code is: bool isspc(char c) { return c == '\n' || c == '\r' || c == '\t' || c == ' '; } The asm is: isspc(char): mov ecx, edi cmp cl, 33 setb dl movabs rax, 4294977024 shr rax, cl and al, dl ret Below is a "Claude Explain" window with: The function isspc(char) is compiled to an efficient bit manipulation technique to check for whitespace characters. Let's break down the assembly instructions: mov ecx, edi Copies the input character from the edi register (first function argument) to ecx cl will contain the lowest 8 bits (the character) cmp cl, 33 Compares the character against decimal 33 This is a preliminary check to quickly filter out non-whitespace characters setb dl Sets the dl register to 1 if the character is below 33 (space, tab, newline, etc.) Uses a conditional set instruction movabs rax, 4294977024 Loads a pre-computed 64-bit constant This constant represents a bit mask for whitespace detection shr rax, cl Shifts the bit mask right by the character's value This dynamically positions the mask based on the input character and al, dl Performs a bitwise AND between the shifted mask and the previous condition Produces the final boolean result in al ret Returns the result (0 or 1) in al This implementation is a highly optimized branchless method for checking whitespace characters, using bit manipulation instead of multiple comparisons. It avoids conditional jumps, which can be slower on modern CPUs. The code checks for space (' '), newline ('\n'), carriage return ('\r'), and tab ('\t') in a single, efficient operation.

Experimenting with something like this for @compiler-explorer.com - wondering what your thoughts are? AI is getting everywhere, and can be divisive. I'm hoping something like this - so long as I can get the output quality high enough - is a net benefit to help folks learn more about their code.

23.05.2025 20:09 👍 49 🔁 6 💬 21 📌 1
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Stripe Sessions 2025 | Product keynote YouTube video by Stripe

We’ve been busy.

Starting now… www.youtube.com/live/AWXAd2G...

07.05.2025 16:04 👍 1 🔁 0 💬 0 📌 0
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Introducing Kermit: A typeface for kids - Microsoft Design Using design to empower children by making reading easier, improving comprehension, and helping dyslexics.

New font from Microsoft.

I like it.

It’s not Comic Sans.

microsoft.design/articles/int...

17.04.2025 01:14 👍 5 🔁 0 💬 0 📌 0

Sofle Low Profile Wireless

github.com/josefadamcik...

15.04.2025 16:10 👍 2 🔁 0 💬 0 📌 0
Post image Post image Post image

Ergo mech portable setup… 3 modes:

1. Full: best ergonomics. Takes about 20 seconds to setup.

2: Quick: busting out laptop quickly. Takes about 5 seconds.

3: Tiny: works on lap, plane tray, etc.

15.04.2025 04:12 👍 8 🔁 0 💬 1 📌 0

The Studio S1E2 is an incredible piece of self-referential cinematography

06.04.2025 04:50 👍 5 🔁 0 💬 0 📌 0
Introducing the Stripe Agent Toolkit
Introducing the Stripe Agent Toolkit YouTube video by Stripe Developers

March 19, Stripe's hosting a live office hours on Stripe's open source Agent Toolkit.

(Our team is hiring btw)

www.youtube.com/watch?v=vdXP...

06.03.2025 20:08 👍 2 🔁 0 💬 0 📌 0

Try Atlas

Let us know how it goes

08.02.2025 18:01 👍 2 🔁 0 💬 1 📌 0

We’ll know we’ve reached AGI when we see models that can figure out the naming convention of models.

05.02.2025 14:25 👍 4 🔁 1 💬 0 📌 0
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Everyone gets bidirectional BFS wrong People really need to stop blindly copying code from the Internet.

What happens when LLMs train on code that's popular but wrong? zdimension.fr/everyone-get... explores this, with interactive diagrams exploring the error

04.02.2025 19:24 👍 85 🔁 19 💬 3 📌 1
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GitHub - monasticacademy/httptap: View HTTP/HTTPS requests made by any Linux program View HTTP/HTTPS requests made by any Linux program - monasticacademy/httptap

httptap.

How this tool decrypts https traffic is fascinating and elegant.

How the tool was made is even more so.

github.com/monasticacad...

05.02.2025 04:38 👍 4 🔁 1 💬 0 📌 0
Post image

Looking at a decade of GitHub stars on one of my projects.

It hit Hacker News front page twice. Pretty obvious when.

But aside from that, it shows steady and remarkably constant organic growth. I have no idea how, and I'd like to learn more.

How do you discover new projects?

01.02.2025 19:21 👍 4 🔁 0 💬 0 📌 0
Hex dump of an executable program, with ASCII art of spiders and a text warning about them.

Hex dump of an executable program, with ASCII art of spiders and a text warning about them.

I just built a hybrid 16-bit MS-DOS/32-bit Windows executable by hand in NASM so that both parts could share common data sections. To fully conform to the PE specs (which I prefer, for long-term compatibility), the file size must be rounded up to the nearest 512 bytes. So I had some space left over…

22.01.2025 00:36 👍 90 🔁 21 💬 1 📌 0

Canada allowed

22.01.2025 19:34 👍 1 🔁 0 💬 1 📌 0
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Software Engineer, Experimental Projects Help increase the GDP of the internet as part of our Data & Data Science team.

Come work with me

stripe.com/jobs/listing...

22.01.2025 16:56 👍 6 🔁 2 💬 1 📌 0

The Imperial March. The most iconic Star Wars theme.

But it was never in the original Star Wars! (Introduced in Empire Strike Back)

17.01.2025 16:06 👍 1 🔁 0 💬 0 📌 0

Oh wow… I just stumbled across @hofferth.net, who’s designed many many many many exciting Mac Mini enclosures!

01.01.2025 01:29 👍 4 🔁 0 💬 0 📌 0
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Things we learned about LLMs in 2024 A lot has happened in the world of Large Language Models over the course of 2024. Here’s a review of things we figured out about the field in the past …

A great summary of LLMs in 2024 by
@simonwillison.net

simonwillison.net/2024/Dec/31/...

01.01.2025 01:22 👍 4 🔁 0 💬 0 📌 0