In Jain Dharma, idli and dosa (as normally made) are generally not considered proper Jain food, especially for anyone trying to follow aahir‑niyam a bit strictly.

Reason in simple terms:

1. Fermentation = many living beings (nigod etc.)

- Idli/dosa batter is kept for many hours or overnight to “sour” / rise. - In this time, countless microorganisms come into existence and multiply. - When we later cook and eat that batter, those living beings are destroyed. - This is avoidable himsā, so Jain shāstra and ācāryas discourage such food.

1. Vāsi (not fresh) food

- Batter is purposely kept for a long time, often overnight. - Jain rules for householders advise eating fresh, same‑day food, and avoiding food kept long or overnight unless absolutely necessary. - So idli/dosa batter becomes “vāsi” and is therefore not ideal.

1. Both Digambar and Shvetāmbara view

- In both traditions, fermented items (idli/dosa, yeast breads, vinegar, alcohol, etc.) are traditionally avoided. - During stricter periods like Paryushan, Das‑Lakshan, Aatham/Chaudas, such foods are almost always clearly prohibited.

1. What many Jain families do in practice

- Very strict practitioners: avoid idli/dosa completely, all the time. - Some more “liberal” families: - May still eat idli/dosa, but know that it is not according to ideal Jain aahar. - Often avoid them at least on tithis (Aatham/Chaudas), Paryushan, Chaturmās niyam, upvās / pachakkhān days, etc.

So, according to Jain principles of ahimsā and fresh, sattvik food:

• Ideal / shāstra‑based answer: Idli and dosa made by fermentation should be avoided.
• If you wish to progress in Jain aachar, it is better to slowly reduce and then stop such fermented foods.

There is a related discussion you can read here: Isn’t dosa/idli discouraged because of fermentation?