I Built A Retirement Countdown With AI. Here’s What I Learned

🔍 Read the full analysis: I Built A Retirement Countdown With AI. Here’s What I Learned on ThorstenMeyerAI.com

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Thorsten Meyer says an AI coding agent helped him build and publish Altersteilzeit, a free web app for counting down the working days in Germany’s partial-retirement block model, in five days. In an account published October 13, Meyer describes a project that grew from a one-minute animated film into a site with a daily countdown, games and multilingual narration, while emphasizing that he supplied the concept, made key choices and approved the releases.

Meyer says the project began on Monday, September 28, 2026, with a request for a short film about Altersteilzeit. Under the block model he describes, a person works as usual during an active phase and then enters a period away from work of equal length; a 4:4 arrangement, for example, pairs four years of work with four years off. The app is designed to count the working days remaining in either phase.

According to Meyer, the public version was online by Friday, October 2. Users enter the start date of one phase and choose a model from 1:1 to 5:5. The app calculates the other date and counts weekdays, subtracting public holidays for the selected German federal state and leave entered by the user. It then uses that information for a daily display, a narrated film and a collection of games.

The daily view includes milestones and a progress ring, and Meyer says users can export milestones to a calendar, print a countdown calendar and find bridge days. He describes the game collection as 19 ways to play, with the active years represented as levels and later years depicted in settings such as a seaside mini-golf course or sailing race. His account also lists seven languages and five German dialects, team countdowns, badges and legal pages.

Where AI Helped—and Where Meyer Decided

The account offers a concrete example of how an AI coding agent can contribute to a small software project across more than code. Meyer says the agent handled implementation, testing, deployment tasks, translations, voice clips and sound effects. He reports that the work included about 18,000 lines of JavaScript and Python, 15 test scripts and 1,224 voice clips. Those figures come from the project’s creator and have not been independently verified here.

Meyer’s description also makes clear that speed did not mean the project ran without human direction. He says he chose the app’s tone and central imagery, decided which voices and dialects to use, and reviewed the releases. That distinction matters to readers considering AI-assisted development: the account documents one creator’s workflow, but it does not establish how quickly or reliably similar tools will perform on other projects.

The app’s stated privacy design is another part of its significance. Meyer says there are no accounts, cookies or tracking, and that calculations happen in the browser. Shared dates are placed after the hash mark in a web address, which he says keeps them out of the request sent to the server. These are claims about the app’s implementation in the source account, rather than an independent privacy audit.

From One-Minute Film to Public App

Altersteilzeit is a German arrangement for reducing or structuring work before retirement. Meyer’s app focuses on the block model: a period of regular work followed by a period away from work. The countdown depends on the dates and work calendar a user supplies, including public holidays for the relevant German state and entered leave.

Meyer says the project expanded over five days and 24 commits. The first day brought the film, date calculations and game prototypes; later work added the daily view, translations, more games, sound, dialects and the bridge-day finder. He says every commit was co-authored by Claude Opus 5.5, which he used as a coding agent. His account describes his own project history and does not compare the tool with other development methods.

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

— Thorsten Meyer

What the Project Account Cannot Establish

The source is Meyer’s own account, published on his website. It does not provide an independent review of the app, its calculations, accessibility, privacy protections or the reported development metrics. It is also unclear from the account how the app handles unusual work schedules, different rules around leave, or changes to holiday calendars beyond the inputs it describes.

Meyer says the application is free and that its calculations run in the browser, but the account does not state whether the app has been audited or how those claims have been tested. Nor does it provide user numbers, feedback or evidence about whether the app has helped people plan their retirement dates. The listed game totals and language counts describe the project at publication, not necessarily its current state.

Check the App and Its Calendar Rules

Meyer’s account describes Altersteilzeit as publicly available, but does not announce a specific next release or development milestone. Readers interested in using it would need to check the live site for the current feature set and enter their own dates, state holidays and leave. People making employment or retirement plans should confirm the relevant dates and rules with their employer or an appropriate official source rather than treating a countdown as a determination of their entitlements.

Any later assessment of the project would depend on evidence beyond the creator’s report: for example, an independent review of the calculations and privacy design, as well as information about user experience and ongoing maintenance. No such review or follow-up results are included in the source material.

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 period away from work of equal length.

What does the countdown app calculate?

Users enter the start date of one phase and choose a model from 1:1 to 5:5. Meyer says the app calculates the other date and counts weekdays, minus public holidays for the selected German state and leave entered by the user.

What did the AI coding agent contribute?

Meyer says the agent helped with software development, testing, translations, audio production and deployment. He says he set the concept and tone, made product decisions and approved releases.

Does the source independently verify the app’s claims?

No. The information comes from Meyer’s account of his own project. The source does not include an independent audit of the calculations, privacy design or reported development figures.

Is the app’s countdown a substitute for employment advice?

No such status is established in the account. Users should verify work dates, holiday rules and employment arrangements with their employer or an appropriate official source before relying on them for planning.

Source: ThorstenMeyerAI.com