Yes, in normal Jain practice peanuts are allowed.

A few simple points:

• Peanuts (singdāna / mungfali) are considered seeds/legumes, not a “root-vegetable” like potato, onion, garlic, etc.
• Traditional Jain maryādā generally permits peanuts and even peanut oil, as long as the other rules are followed (no onion–garlic, fresh food, before sunset, etc.).
• Some very strict sādharmik families or during special vrats (upvās, ayambel, etc.) may avoid heavy items like nuts by extra niyam – that is a personal or guru‑based discipline, not a general Jain rule.

So: Yes, Jains can eat peanuts, unless your family/guru has given a special niyam not to.

You can also see an overview of allowed Jain foods here: