Yes, you can absolutely ask for a reference or testimonial from Wripple clients after completing a project but be aware that some clients may decide not to provide this for a variety of reasons. That said, many clients are happy to support talent members they've enjoyed working with, as long as your request is respectful and well-timed.
Here are a few best practices:
Ask soon after the project ends, while the work is still fresh in their mind.
Be polite and specific. Mention what kind of reference you're looking for (e.g., a quote for your website, a LinkedIn recommendation, or a contactable reference).
Make it easy for them by offering to draft a sample or provide guiding questions, if appropriate.
Follow their guidelines. Many clients do not want their name and/or company shared online, so please keep it anonymous when requested.
Respect their decision if they decline or don't have time.