Building With AI: 16 Versions Of A Retirement Countdown In Five Days

🔍 Read the full analysis: Building With AI: 16 Versions Of A Retirement Countdown In Five Days on ThorstenMeyerAI.com

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Thorsten Meyer says he built and released Altersteilzeit, a free web app for people counting down to partial retirement in Germany, in five days with help from the Claude Opus 5.5 coding agent. The project grew from a request for a one-minute animated film into a browser-based countdown with a film, games and multilingual features, while Meyer directed the work and approved releases.

Meyer’s account says he began the project on Monday, September 28, asking the agent for a short film about the two phases of German Altersteilzeit in the block model: a period of regular work followed by an equally long period away from work. He says the app was online by Friday, October 2. A 4:4 arrangement, for example, pairs four years of active work with four years in the passive phase.

The app asks users for the start date of either phase and their model, which Meyer says ranges from 1:1 to 5:5. It then calculates the corresponding date and remaining working days, accounting for weekdays, public holidays in the user’s German federal state and entered leave. The daily view includes milestones and a saying of the day, with options such as a calendar export, printable calendar and bridge-day finder.

Other features described by Meyer include a short narrated film, a game collection tied to the years of the active phase, team countdowns and badges. His article gives different counts at different points: it first describes the release as having 19 game modes, then says the game was playable in 15 modes. Meyer also says the app supports seven languages and five German dialects, while the production account refers to work on 12 languages. Those figures may refer to different stages or content, but the article does not fully explain the distinction.

A Countdown Built Around Workdays

The project illustrates a practical use of AI coding tools: helping one developer assemble a tailored application that combines date calculations, interface design, media and browser games. The subject is specific—people approaching the end of an Altersteilzeit arrangement—but the development account also shows the limits of treating speed as the whole story. Meyer says the agent handled substantial coding and production work, while he supplied the concept, set the tone and made decisions that shaped the finished product.

For users, the main appeal is the way the app translates a long employment timeline into daily progress and milestones. It is more than a date calculator, according to Meyer’s description: users can use the countdown, film and games with the same dates. At the same time, the article does not provide user numbers, independent testing or evidence of how well the calculations work across every state and individual leave arrangement.

Meyer also describes privacy as a design rule. He says the app has no accounts, cookies or tracking, with calculations performed in the browser. Shared dates are placed after the “#” in a web address, which his article says is not sent to a server in a normal web request. These are claims in the developer’s account; readers would need to examine the app and its implementation to verify them independently.

From Film Request to Web App

Altersteilzeit is a German partial-retirement arrangement. In the block model described by Meyer, a person works as usual during an active phase and then spends an equivalent period in a passive phase. Because the countdown depends on workdays, holidays and leave, a calendar-day total alone may not reflect how many working days remain.

Meyer says the app’s game design uses calendar time as its structure. In examples from his account, a maze’s columns represent months and its cells represent weeks; in another game, a full row represents two working weeks. Leave and public holidays can affect gameplay. He says the games use original names rather than names associated with other companies’ trademarks.

The development timeline in the article runs from a film request on September 28 to an online release on October 2. Meyer reports that the agent helped with engineering, testing, translation, voice clips, sound effects and deployment. He says all 24 commits were co-authored by Claude Opus 5.5. His account is a first-person description of the process, not an independent audit or a third-party review.

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

— Thorsten Meyer, describing the project

Feature Counts Need Clarification

The source is Meyer’s own account, and no independent confirmation of the app’s features, code, privacy behavior or development timeline was supplied. It is also unclear whether the different counts for game modes and supported languages refer to separate versions, content categories or a change during development. Meyer says the project had 19 game modes in one passage and 15 in another, and refers to seven languages, five dialects and production work covering 12 languages.

The article does not give the app’s user numbers, operating costs, accessibility details, ongoing maintenance plan or whether the calculations have been reviewed against all relevant employment and holiday rules. It also does not establish whether the app is suitable for official retirement or employment decisions. The described countdown should be understood as the app’s calculation, not legal or financial advice.

Use and Verification Ahead

Meyer’s account describes the app as online after his approval on October 2, but the supplied material gives no schedule for future updates or independent review. The next practical step for readers interested in using it is to inspect the live app’s date calculations, privacy disclosures and supported options before relying on its countdown.

Further reporting could establish how the app performs across German federal states, whether its privacy claims match its deployed code, and how many people use it. Meyer’s article also leaves open whether the reported game and language counts describe the release version or the development process at different points.

Key Questions

What is Altersteilzeit?

It is a German partial-retirement arrangement. In the block model described by Meyer, a person works during an active phase and then has a passive phase of equal length.

What does the app calculate?

Meyer says users enter the start date of either phase and choose a model from 1:1 to 5:5. The app calculates the other date and counts working days, taking account of weekdays, state public holidays and leave entered by the user.

How long did development take?

Meyer says work began on September 28, 2026, and the app was online by October 2—five days later. This timeline comes from his first-person account and was not independently verified in the supplied material.

Did the AI agent build the app on its own?

No. Meyer says the agent handled coding and other production tasks, but he provided direction, made product and creative decisions, reviewed the work and approved releases.

Are the app’s privacy and feature claims independently verified?

Not in the source material provided. Meyer says the app has no accounts, cookies or tracking and runs its calculations in the browser, but no independent technical review or usage data was included.

Source: ThorstenMeyerAI.com