I just implemented x402, a standard for HTTP-native payments that lets AI agents pay autonomously for services — no accounts, no sessions, just 402 Payment Required + crypto.
Built a facilitator, wired it to Optimism, and learned a lot about trust models along the way.
www.fretchen.eu/blog/22
Built a facilitator, wired it to Optimism, and learned a lot about trust models along the way.
www.fretchen.eu/blog/22
First experiences with the x402 Standard for paying AI agents | fretchen.eu
I implemented the x402 payment standard for AI agents to autonomously pay for image generation services without accounts or sessions.
www.fretchen.eu
December 29, 2025 at 1:28 PM
I just implemented x402, a standard for HTTP-native payments that lets AI agents pay autonomously for services — no accounts, no sessions, just 402 Payment Required + crypto.
Built a facilitator, wired it to Optimism, and learned a lot about trust models along the way.
www.fretchen.eu/blog/22
Built a facilitator, wired it to Optimism, and learned a lot about trust models along the way.
www.fretchen.eu/blog/22
I implemented the x402 payment standard for AI agents to autonomously pay for image generation services without accounts or sessions.
First experiences with the x402 Standard for paying AI agents
I implemented the x402 payment standard for AI agents to autonomously pay for image generation services without accounts or sessions.
www.fretchen.eu
December 30, 2025 at 7:08 AM
I implemented the x402 payment standard for AI agents to autonomously pay for image generation services without accounts or sessions.
I got interested in ethereum and the blockchain because I wanted to understand if it might be possible to have decentral networks of quantum computers or AI agents. As I am learning, I now implemented some guides that would allow others to join the experiment: www.fretchen.eu/agent-onboar... #eth
Agent Onboarding | fretchen.eu
Learn how to register your AI service as an agent on fretchen.eu. Follow EIP-8004 standards for trustless agent discovery and on-chain verification.
www.fretchen.eu
December 7, 2025 at 8:04 PM
I got interested in ethereum and the blockchain because I wanted to understand if it might be possible to have decentral networks of quantum computers or AI agents. As I am learning, I now implemented some guides that would allow others to join the experiment: www.fretchen.eu/agent-onboar... #eth
Just discovered that a bot network exploited my ImageGen NFT contract — all to steal… 80 cents. 😅
Analyzed the wallets, found a 2.5-year-old operation extracting >100k USDC across chains.
Patched the contract, published the write-up, and the bots are weirdly impressive.
www.fretchen.eu/blog/21
Analyzed the wallets, found a 2.5-year-old operation extracting >100k USDC across chains.
Patched the contract, published the write-up, and the bots are weirdly impressive.
www.fretchen.eu/blog/21
How bots exploited my ImageGen contract - and how I fixed it | fretchen.eu
A bot network exploited a vulnerability in my GenImNFT contract, extracting over 80 cents. Here's how they did it, how I fixed it, and what the forensic analysis revealed about the bot network that se...
www.fretchen.eu
December 2, 2025 at 5:21 PM
Just discovered that a bot network exploited my ImageGen NFT contract — all to steal… 80 cents. 😅
Analyzed the wallets, found a 2.5-year-old operation extracting >100k USDC across chains.
Patched the contract, published the write-up, and the bots are weirdly impressive.
www.fretchen.eu/blog/21
Analyzed the wallets, found a 2.5-year-old operation extracting >100k USDC across chains.
Patched the contract, published the write-up, and the bots are weirdly impressive.
www.fretchen.eu/blog/21
A bot network exploited a vulnerability in my GenImNFT contract, extracting over 80 cents. Here's how they did it, how I fixed it, and what the forensic analysis revealed about the bot network that seemingly extracts substantial sums.
How bots exploited my ImageGen contract - and how I fixed it
A bot network exploited a vulnerability in my GenImNFT contract, extracting over 80 cents. Here's how they did it, how I fixed it, and what the forensic analysis revealed about the bot network that seemingly extracts substantial sums.
www.fretchen.eu
December 3, 2025 at 7:07 AM
A bot network exploited a vulnerability in my GenImNFT contract, extracting over 80 cents. Here's how they did it, how I fixed it, and what the forensic analysis revealed about the bot network that seemingly extracts substantial sums.
In the last few weeks I looked a bit into ways that democracy could work outside of the confines of nation-states. And I made an essay out of it... All inspired by the incredible interviews of Lea Ypi...
www.fretchen.eu/blog/20
www.fretchen.eu/blog/20
Democracy beyond the nation-state - What is there ? | fretchen.eu
When climate, water, and digital challenges cross borders but democracy doesn't, what's the alternative? This narrative essay compares confederation, federation, and cosmopolitan democracy through thr...
www.fretchen.eu
November 26, 2025 at 5:40 PM
In the last few weeks I looked a bit into ways that democracy could work outside of the confines of nation-states. And I made an essay out of it... All inspired by the incredible interviews of Lea Ypi...
www.fretchen.eu/blog/20
www.fretchen.eu/blog/20
Live as a builder is hard sometimes. In October I go a few hundred visitors. Now I decided to see how they engage with the different buttons and features on my website. The result is: 0 engagement :( Let's see what it is, but this is really painful...
Any recommendations out there ?
Any recommendations out there ?
November 16, 2025 at 2:37 PM
Live as a builder is hard sometimes. In October I go a few hundred visitors. Now I decided to see how they engage with the different buttons and features on my website. The result is: 0 engagement :( Let's see what it is, but this is really painful...
Any recommendations out there ?
Any recommendations out there ?
I really love the power that games have to teach me new things. This website has pushed this to a whole other level as it collects plenty of really thoughtful and educative games.
nonzerosum.games
nonzerosum.games
nonzerosum.games
November 2, 2025 at 3:43 PM
I really love the power that games have to teach me new things. This website has pushed this to a whole other level as it collects plenty of really thoughtful and educative games.
nonzerosum.games
nonzerosum.games
Over the last few weeks I tried to make my website more discoverable for external users and search engines. The neat thing. It actually increased the traffic threefold. Here are my experiences:
www.fretchen.eu/blog/19/
www.fretchen.eu/blog/19/
Making My Site Discoverable - SEO, Webmentions, and a Traffic Spike | fretchen.eu
I overhauled my site's SEO with Schema.org markup and replaced Giscus comments with Webmentions. The timing coincided with a surprising 200% traffic increase. Here's what I learned about making conten...
www.fretchen.eu
October 27, 2025 at 4:06 PM
Over the last few weeks I tried to make my website more discoverable for external users and search engines. The neat thing. It actually increased the traffic threefold. Here are my experiences:
www.fretchen.eu/blog/19/
www.fretchen.eu/blog/19/
I overhauled my site's SEO with Schema.org markup and replaced Giscus comments with Webmentions. The timing coincided with a surprising 200% traffic increase. Here's what I learned about making content discoverable.
Making My Site Discoverable - SEO, Webmentions, and a Traffic Spike
I overhauled my site's SEO with Schema.org markup and replaced Giscus comments with Webmentions. The timing coincided with a surprising 200% traffic increase. Here's what I learned about making content discoverable.
www.fretchen.eu
November 1, 2025 at 12:50 PM
I overhauled my site's SEO with Schema.org markup and replaced Giscus comments with Webmentions. The timing coincided with a surprising 200% traffic increase. Here's what I learned about making content discoverable.
Fun fact. My AMO lectures currently have 10 to twenty daily visitors from …. Singapore. They are now the top page
www.fretchen.eu/quantum/amo
www.fretchen.eu/quantum/amo
Notes and Thoughts | fretchen.eu
Blog, notepad, whatever you want to call it.
www.fretchen.eu
October 21, 2025 at 4:16 PM
Fun fact. My AMO lectures currently have 10 to twenty daily visitors from …. Singapore. They are now the top page
www.fretchen.eu/quantum/amo
www.fretchen.eu/quantum/amo
Thanks to this great blog post I have been able to add #webmentions to my website. It explains in detail how you can get comments etc to your static blog. A flexible alternative to #giscus and friends.
janmonschke.com/adding-webme...
janmonschke.com/adding-webme...
Adding webmentions to your static blog | Jan Monschke
The portfolio and blog of Jan Monschke
janmonschke.com
October 18, 2025 at 3:25 PM
Thanks to this great blog post I have been able to add #webmentions to my website. It explains in detail how you can get comments etc to your static blog. A flexible alternative to #giscus and friends.
janmonschke.com/adding-webme...
janmonschke.com/adding-webme...
I built an NFT system for generative AI to test if smart contracts can work for quantum computing.
Spoiler: payments and ownership work great (10¢ per image, <1¢ blockchain costs).
The hard problem? Trustless verification.
www.fretchen.eu/blog/18
Ideas welcome.
Spoiler: payments and ownership work great (10¢ per image, <1¢ blockchain costs).
The hard problem? Trustless verification.
www.fretchen.eu/blog/18
Ideas welcome.
Quantum Smart Contracts II - What can we learn from NFTs for quantum computing with smart contracts ?
Can blockchain solve quantum computing's access problem? I tested the architecture with AI NFTs—here's what worked, what didn't, and what's still unsolved.
www.fretchen.eu
October 17, 2025 at 5:14 AM
I built an NFT system for generative AI to test if smart contracts can work for quantum computing.
Spoiler: payments and ownership work great (10¢ per image, <1¢ blockchain costs).
The hard problem? Trustless verification.
www.fretchen.eu/blog/18
Ideas welcome.
Spoiler: payments and ownership work great (10¢ per image, <1¢ blockchain costs).
The hard problem? Trustless verification.
www.fretchen.eu/blog/18
Ideas welcome.
Can blockchain solve quantum computing's access problem? I tested the architecture with AI NFTs—here's what worked, what didn't, and what's still unsolved.
Quantum Smart Contracts II - What can we learn from NFTs for quantum computing with smart contracts ?
Can blockchain solve quantum computing's access problem? I tested the architecture with AI NFTs—here's what worked, what didn't, and what's still unsolved.
www.fretchen.eu
November 1, 2025 at 12:55 PM
Can blockchain solve quantum computing's access problem? I tested the architecture with AI NFTs—here's what worked, what didn't, and what's still unsolved.
When I saw the #nobelprize in physics today, I had two thoughts.First thought: Finally the superconducting qubits got it. Their stuff is taught in undergrad level now, so talk about impact.
www.nobelprize.org/prizes/physi...
www.nobelprize.org/prizes/physi...
Nobel Prize in Physics 2025
The Nobel Prize in Physics 2025 was awarded jointly to John Clarke, Michel H. Devoret and John M. Martinis "for the discovery of macroscopic quantum mechanical tunnelling and energy quantisation in an...
www.nobelprize.org
October 7, 2025 at 3:30 PM
When I saw the #nobelprize in physics today, I had two thoughts.First thought: Finally the superconducting qubits got it. Their stuff is taught in undergrad level now, so talk about impact.
www.nobelprize.org/prizes/physi...
www.nobelprize.org/prizes/physi...
It has been a while that I started to think about the possibility to use #blockchain payments to democratize the access to #quantum computers. Finally, I started to write it up. I am looking forward to your feedback and best would be links to other people curious about this:
www.fretchen.eu/blog/17
www.fretchen.eu/blog/17
Can we decentralize access to quantum computing with smart contracts ?
Blog, notepad, whatever you want to call it.
www.fretchen.eu
October 2, 2025 at 8:12 PM
It has been a while that I started to think about the possibility to use #blockchain payments to democratize the access to #quantum computers. Finally, I started to write it up. I am looking forward to your feedback and best would be links to other people curious about this:
www.fretchen.eu/blog/17
www.fretchen.eu/blog/17
I explore how smart contracts can democratize access to quantum computing resources, enabling privacy-preserving decentralized payments and encrypted NFT results.
Quantum Smart Contracts I - Can we decentralize access to quantum computing with smart contracts ?
I explore how smart contracts can democratize access to quantum computing resources, enabling privacy-preserving decentralized payments and encrypted NFT results.
www.fretchen.eu
November 6, 2025 at 1:54 PM
I explore how smart contracts can democratize access to quantum computing resources, enabling privacy-preserving decentralized payments and encrypted NFT results.
I enabled image editing with simple prompts. You can now upload an image and just change it through a prompt. Any feedback is very welcome.
www.fretchen.eu/en/imagegen
More details will follow soon
www.fretchen.eu/en/imagegen
More details will follow soon
www.fretchen.eu
September 28, 2025 at 7:51 PM
I enabled image editing with simple prompts. You can now upload an image and just change it through a prompt. Any feedback is very welcome.
www.fretchen.eu/en/imagegen
More details will follow soon
www.fretchen.eu/en/imagegen
More details will follow soon
Over the last few weeks I wondered if I might be able to connect LLMs to the beautiful payment possibilities of the web3. In this blogpost I describe how I made it work:
www.fretchen.eu/blog/16/
Still rough around the edges, so any feedback is welcome.
www.fretchen.eu/blog/16/
Still rough around the edges, so any feedback is welcome.
My AI Assistant That Takes ETH Instead of Subscriptions
Blog, notepad, whatever you want to call it.
www.fretchen.eu
August 31, 2025 at 7:03 PM
Over the last few weeks I wondered if I might be able to connect LLMs to the beautiful payment possibilities of the web3. In this blogpost I describe how I made it work:
www.fretchen.eu/blog/16/
Still rough around the edges, so any feedback is welcome.
www.fretchen.eu/blog/16/
Still rough around the edges, so any feedback is welcome.
Alright. I think that this is my very first post on this platform. I like all kind of data, math, physics etc. Nowadays, I do most of them for fun and then write little posts about them on my little website.
www.fretchen.eu/blog/
www.fretchen.eu/blog/
fretchens Blog
Blog, notepad, whatever you want to call it.
www.fretchen.eu
August 26, 2025 at 7:58 PM
Alright. I think that this is my very first post on this platform. I like all kind of data, math, physics etc. Nowadays, I do most of them for fun and then write little posts about them on my little website.
www.fretchen.eu/blog/
www.fretchen.eu/blog/
I migrate academic lectures from LaTeX to modern web formats. Discover solutions for handling equations, references, and static site generation in JavaScript environments.
Moving old lectures
I migrate academic lectures from LaTeX to modern web formats. Discover solutions for handling equations, references, and static site generation in JavaScript environments.
www.fretchen.eu
November 1, 2025 at 11:10 AM
I migrate academic lectures from LaTeX to modern web formats. Discover solutions for handling equations, references, and static site generation in JavaScript environments.
I share my journey from scattered notes to a unified blog using React and Vike. Modern web tech offers speed, simplicity, and full version control over traditional solutions. (http://fretchen.eu/blog/1)
Ideas behind the blog stack
I share my journey from scattered notes to a unified blog using React and Vike. Modern web tech offers speed, simplicity, and full version control over traditional solutions.
fretchen.eu
November 1, 2025 at 7:56 AM
I share my journey from scattered notes to a unified blog using React and Vike. Modern web tech offers speed, simplicity, and full version control over traditional solutions. (http://fretchen.eu/blog/1)