What I Discovered While Making A Retirement Countdown With AI

🔍 Read the full analysis: What I Discovered While Making A Retirement Countdown With AI on ThorstenMeyerAI.com

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Thorsten Meyer says he used the AI coding agent Claude Opus 5.5 to help build and release Altersteilzeit, a free web app for counting down working days in a German partial-retirement arrangement, over five days. The project grew from a request for a one-minute animated film into a site with a daily countdown, a film, 19 games and multilingual features, while Meyer directed the work and approved its releases.

Meyer’s account says the project began on Monday, September 28, when he asked the agent for a short film about the two stages of Altersteilzeit in the block model: an active phase in which a person continues working, followed by a passive phase away from work. He says he approved the app for release on Friday, October 2. In a 4:4 model, for example, each phase lasts four years.

Users enter the start date of either phase, choose a model from 1:1 to 5:5 and provide details such as their German federal state and leave allowance. The app calculates working days, excluding weekends and the state’s public holidays, and presents the result through a daily countdown, milestones and a progress display. Other features include calendar exports, a printable cross-off calendar and a finder for public-holiday bridge days.

The site also includes an animated film about the user’s two phases and a set of 19 3D games, according to Meyer. He describes the games as mapping calendar time into play, with examples including a maze based on months and weeks and a game in which emails represent working days. Meyer says all 24 project commits were co-authored by Claude Opus 5.5. His account describes the agent producing code, tests, text, audio and deployment work, while he set the tone, made design and editorial decisions, checked the results and authorized releases.

Human Decisions in an AI-Built App

The project offers a specific example of how an AI coding agent can contribute to a small public-facing software product, beyond generating a code snippet. Meyer says the agent helped with engineering, testing, localization, audio production and deployment, compressing a varied workload into a five-day development period. That is his account of this project, not an independently measured comparison with a human-only team or a guarantee of similar results elsewhere.

The development story also shows where Meyer says human judgment remained central. He chose the core idea, humor and visual approach, selected voices and dialects, reviewed legal-page details and approved the finished work. For readers weighing AI-assisted development, the distinction matters: the agent performed many production tasks, but the product’s priorities and release decisions still had a human owner.

Privacy is another stated design choice. Meyer says the app has no accounts, cookies or tracking and calculates dates in the browser. Shared dates, he says, are stored after the hash mark in a web address, which browsers do not send to the server in a standard request. Those points describe the developer’s implementation claims; the account does not include an independent privacy or security audit.

From Film Request to Countdown Site

Altersteilzeit is a German partial-retirement arrangement. In the block model described by Meyer, a worker spends one phase working as usual and a second phase away from work; the app is designed to count the working days until the change. Its intended audience is people who want a practical, personalized way to follow that timeline, rather than a general retirement-planning tool.

Meyer’s timeline describes rapid additions across five days. He says the first day brought the film, date calculations, early game prototypes and an initial public release. The following days added language support, the daily view, more games, a bridge-day finder, badges, narration and sound effects. On the fifth day, he says, he reviewed the work and added five German dialects. The published account calls the app multilingual and refers to seven languages alongside five dialects; it also describes voice production in twelve languages. These different counts refer to different parts of the project and are not fully reconciled in the account.

The account was published on October 13, 2026, after the reported development period. It is a first-person description from the project’s creator, not an independent technical review. Meyer reports about 18,000 lines of JavaScript and Python, 15 test scripts and 1,224 voice clips, but does not provide external verification or comparative productivity data.

“The interesting part is not how much an AI agent can build, but what was still left for me to do.”

— Thorsten Meyer, project creator

Claims Awaiting Independent Checks

The project’s development details and performance figures come from Meyer’s first-person account. The article does not include an independent review of the app’s code, test coverage, accessibility, privacy protections or calculations. It also does not report user numbers, feedback, operating costs or comparisons with a conventional development process.

Some scope details need clarification. The account refers to 19 games in one section and 15 game modes in another, which may describe different counts but are not explained. It also gives differing language totals for the interface, dialects and recorded voices. It is not clear from the account whether all features and translations received the same level of testing or whether the app’s calculations have been checked against official employment or retirement guidance.

The app is presented as a countdown aid, not as a source of legal or financial advice. Whether its date calculations suit an individual’s employment agreement, leave rules or local circumstances remains a matter users would need to verify. The account does not say whether the project will receive ongoing maintenance or how users can report errors.

Testing and Maintenance Ahead

Meyer’s published account does not announce a future release date or a planned development schedule. The immediate next step for readers interested in the tool is to try the public app and check its date assumptions against their own work arrangements and the relevant state holiday calendar. Any use of the countdown for employment planning should be based on verified dates and conditions.

Further reporting could establish how the app performs in use: whether its calculations match independent checks, how users respond to the games and translations, and whether the privacy claims have been reviewed. Meyer’s account also leaves open whether he will publish the code, add features or maintain the site over time. Those points remain unconfirmed.

Key Questions

What is Altersteilzeit?

Altersteilzeit is a German partial-retirement arrangement. In the block model described by Meyer, a person works through an active phase and then has a passive phase away from work.

What does the app calculate?

Users enter a phase start date and choose a model. The app calculates remaining working days, accounting for weekends, the public holidays in the selected German state and leave entered by the user, according to Meyer.

Did the AI agent build the app on its own?

No. Meyer says Claude Opus 5.5 handled coding and other production tasks, but he supplied the direction, made design and content decisions, reviewed results and approved releases.

Is the app’s privacy design independently verified?

The source account says the app has no accounts, cookies or tracking and calculates dates in the browser. It does not describe an independent privacy or security audit, so those statements remain the developer’s claims.

Source: ThorstenMeyerAI.com