According to this Jain site, many Hindu scriptures mention the 1st Jain Tirthankara Rishabha (who the Jain tradition considered the founder of their tradition) and the 22nd Tirthankara Neminath:
Myth # 1 – Jainism was founded by Mahavira Swami.
The Truth- Jainism is an ancient religion that pre-dates lord Mahavira. Herman Kuhn an Indologist and translator of Tattvarthasutra says – "There exists evidence of twenty four enlightened teachers who taught identical knowledge at much earlier times.” According to Britannica Encyclopedia, Lord Parshvanatha, 23rd Jaina Tirthankara was a Historical figure who flourished in 8th Century BCE. (Ref : http://www.britannica.com/ebc/article-9374627 )
From the Buddhist and Jain records, it is clear that Jainism is older than Buddhism and was firmly established at the time of the origin of Buddhism. In the Samannaphala Sutta of the Dighanikaya, there is a reference to the four vows (Chaturyama Dharma) of Parshvanatha. Lord Neminath (22nd Tirthankar) and Lord Rushabh Nath (1st Tirthankar) are mentioned in various Vedas and Hindu Puranas. This proves that Mahavir Swami was a reformer and reviver of already existing Shraman traditions.
Now, I'm aware that the first Tirthankara is mentioned in various Puranas such as the Srimad Bhagavatam where He is depicted as an incarnation of Vishnu:
The eighth incarnation was King Rishabha, son of King Nābhi and his wife Merudevī. In this incarnation the Lord showed the path of perfection, which is followed by those who have fully controlled their senses and who are honored by all orders of life. (Srimad Bhagavatam 1.3.13)
However, I haven't come across any Hindu texts mentioning the 22nd Tirthankara Neminath. So do any texts mention Neminath as this site claims?
Edit: I have found a reference of Neminath in the Yajurveda as per this answer. Are there any other scriptures that supposedly talk about Neminath?