E-signature pioneer company DocuSign has reportedly filed confidentially to go public. TechCrunch on Tuesday published a report citing sources at DocuSign saying that the company had covertly submitted its initial public offering (IPO) filing, and will announce formally in the weeks before its public debut.

DocuSign received a $3 billion valuation in 2015, and has raised over $500 million in investment funding over its 15-year lifespan. The company declined to comment for this story.