The best replacement for flowcharts is pseudocode.

The best alternatives to flowcharts are rated as following:
★★★★★  pseudocode
★★  pseudocode which is better
★  data flow diagrams
★  pseudo code
★  data flow diagram

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Speaking about flowcharts, one probably shouldn't forget about pseudocode.

Other search terms related to flowcharts and their ratings are:
★★★★★ pseudocode
★★ algorithms
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Google Trends

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flowcharts
pseudocode
pseudocode which is better