Carly Stevens and her partner, Tim Gower, attended Surabhi Chauhan's wedding on Nov. 4, 2017. Source: Carly Stevens and Tim Gower

When Surabhi Chauhan, a Delhi-based fund manager, got married last November, roughly 400 guests attended her wedding. Two names on the guest list were people she had never met before: Carly Stevens and Tim Gower. The Australian travel bloggers paid around $200 for a two-day invitation to attend Chauhan's wedding through a start-up called Join My Wedding. "The concept was pretty new," Chauhan told CNBC in an interview, explaining that she came across the start-up while booking her wedding venue. "We were also getting to know people from other countries. We were very much excited and open about it, given the fact that it was new." She and her husband were introduced to Stevens and Gower by one of the start-up's co-founders, Orsi Parkanyi, she said. "We were chatting and coordinating, we had a brief introduction about each of us, what exactly we do, our respective profiles (and) what are the arrangements that will be there, the kind of attire they're supposed to wear — all those conversations happened," Chauhan said.

The wedding tourism business

Here's how Join My Wedding works: Indian couples list details about their weddings on the website, and international travelers can buy tickets to the nuptials they want to attend. Most of the contributions from the tickets go to the couples, but the start-up takes a cut. "If you think about it, there's nothing more cultural than a wedding because you have every cultural element present: The local people, local food, customs, the outfit, the music, basically every cultural element is right there," Parkanyi told CNBC. The co-founder explained that the idea for the start-up came from her own experiences in missing out on her friends' weddings. The decision to focus on Indian weddings was because they are "world-famous" and most non-Indians would not have a chance to attend one unless through personal connections. To date, travelers have attended more than 100 Indian weddings through the start-up, according to Parkanyi.

The rituals process in a Indian Hindu wedding. Navaneeth | Moment | Getty Images

"Experiencing all the cultural elements at once, meaningfully connecting with the locals in India, that's a huge motivating factor for the travelers," she said. "It's a safe experience. You attend an event with hundreds of people, you're a distinguished guest, people look after you." Many travel agencies and tour operators are capitalizing on this developing trend by creating custom tour packages for international travelers to attend Indian wedding ceremonies during their visit. Indian weddings are known for their opulence, customs and traditions that are celebrated over several days — millions of couples get married in the country every year, where there's a growing population and a rising middle class. Experts consider the Indian wedding industry, which is said to be worth about $40 billion and growing around 20 percent a year, to be recession-proof. "As far as the Indian (wedding) market is concerned, it's growing every year," Ashish Boobna, director of weddings and events at Ferns N Petals, a large wedding planning company for affluent Indians. Almost every sector is getting business from the wedding industry, in areas of decor, entertainment, food and hospitality, while new companies are being created to cater to the demands of Indians who are getting married, he said.

'Endless colors'

Boobna explained that wedding tourism is an up and coming trend in India's wedding industry, similar to medical tourism in the health care sector. For some Indian couples, the concept of inviting international travelers to attend their wedding is a way to make the ceremony more extravagant and more "show biz," he said. But others want travelers at their weddings to experience the culture and the rituals. "Foreign tourists are interested in seeing the Indian culture very closely," he added. The celebration, with song and dance, and the elaborate, symbolic rituals make Indian weddings very vibrant and that's what draws in interest from international travelers, according to Sahajanand Sharma, a tour guide based in India. "Things in Western weddings are pretty — the Church rituals you do, you probably do an after party. But everything is sort of very structured, whereas here, there's always ... someone would start dancing, there's endless colors, there's endless food, there are endless rituals," he said. Sharma also recently got married and invited about 15 to 20 of his former clients from the U.S. and Europe to join the ceremony. "I was traveling with them, with each one of them ... we sort of know each other really well," he told CNBC in an interview before the wedding. On top of that, Sharma said a tour guide friend asked if he could bring another visitor to the wedding. "I said 'why not?' We're 70 people, we can definitely accommodate a couple more."

'Part of the family'