NEW DELHI—Some of the biggest names in the startup world will gather in India’s capital on Saturday, hoping Prime Minister Narendra Modi will keep his promise to loosen regulations that entrepreneurs say strangle new businesses.

Uber Technologies Inc.’s Travis Kalanick and billionaire Masayoshi Son, the founder of SoftBank Group, will join India’s most-valuable startups for a one-day summit in Delhi where Mr. Modi will outline his plans to encourage entrepreneurship.

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