What visa should a former Indian citizen apply for if they don't have OCI?

I think the important thing is why you are travelling and which passport you will use.

Once you have acquired foreign citizenship, you cannot travel to India using your old Indian passport. Your current foreign passport is the travel document for the visa application.

If you're simply going for a holiday or family visit, check whether your Canadian passport qualifies for an e-Tourist Visa. Canada is currently listed among the nationalities eligible for India's e-Visa system.

But because you are a former Indian citizen, I would also look at the regular Foreigners of Indian Origin / Entry Visa route. The regular visa provision specifically lists “Foreigners of Indian Origin” as a visa category and requires proof of Indian origin.

I wouldn't choose based solely on which visa has the longer validity. Check the current instructions of the Indian mission handling your application because individual circumstances and document requirements can differ.

One thing that helped me was keeping all my old Indian citizenship documents together.

I had:

• Current foreign passport
• Cancelled Indian passport
• Surrender Certificate
• Birth certificate showing my Indian origin

The Surrender Certificate doesn't mean you still have Indian citizenship. It is evidence connected with the surrender of the Indian passport/citizenship after acquiring foreign nationality.

For the visa itself, the official Indian Visa Online information lists a Foreigners of Indian Origin category and says proof of being of Indian origin is required.

If you are applying for an e-Visa instead, don't assume that being of Indian origin automatically qualifies you. The e-Visa rules are based on your current nationality/passport and the purpose of travel, among other conditions.

So I'd compare the current Entry Visa and e-Tourist Visa requirements before submitting the application.

I was in almost the same situation. I’m a former Indian citizen and became a British citizen, but I didn’t have an OCI when I made my last trip to India.

For my situation, I looked at the regular Indian visa categories for foreigners of Indian origin rather than treating myself as an Indian passport holder. The Indian Visa Online site has a separate category for Foreigners of Indian Origin, with proof of Indian origin required.

I submitted my current foreign passport along with documents showing my previous Indian citizenship. My old Indian passport and surrender-related documents were useful for establishing the connection.

I would not assume that an OCI is required before you can travel. OCI and an Indian visa are different things.

If your only purpose is a short family visit, an e-Tourist Visa may also be an option if your current nationality and circumstances meet the e-Visa requirements. The official e-Visa site says eligible foreign nationals can use the e-Tourist category for tourism and casual visits to friends or relatives.