Every case study starts with what could not change.

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The same components had to run on Next.js, Vite and React Native without the web and mobile versions drifting apart.▍

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More than thirty construction companies each needed their own colors, logos and imagery from the same set of about a hundred components.▍

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Generated code arrives faster than a person can carefully read it.▍

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The marketplace was the client's only source of revenue, so nothing could be taken offline or rewritten in place.▍

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The analytics layer had to take writes at volume, serve live reads and aggregate a whole year quickly, all at once.▍

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Standard web analytics measures neither the position an advertiser pays for nor the calls they get.▍

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Every customer renewed on a different date, and nobody could watch several thousand expiry dates by hand.▍

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Five kinds of user did different work on the platform, but every payment, branding or security change had to reach all five.▍

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The applications included biometrics, and the people the agents visited often had no connection.▍

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Regulation required video identification, and each session's record had to hold up in a review years later.▍

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An issued invoice must not change when its template does.▍

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Neither the passport chip nor the payment terminal had a library worth using.▍

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The BI tool generates the queries and customers' saved reports depend on the schema, so neither could change.▍

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The product kept doing the same work for the same users, and nothing was decommissioned.▍

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Whether a person may open a document had to be answered instantly, however long the chain behind it.▍

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SAP had to remain the system everything starts from, with the new ERP running alongside it.▍

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The forms had to match the site's design without losing the tracking cookie that ties each submission to a visit.▍

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The law or a license decided which payment partner a product had to use.▍