Here is a simple and commonly recited Simandhar Swami mantra:

1. Short name‑smaran mantra

``` Shri Simandhar Swami Bhagwan ni Jay Jai Simandhar Swami ```

You can repeat this many times with devotion and focus on his pure, omniscient form in Mahavideh Kshetra.

2. Slightly longer bhakti mantra

``` Om Shri Simandhar Swami Bhagwate Namah Om Shri Simandhar Swami Namah ```

You may chant either of these:

• Sit quietly, keep back straight.
• Remember Simandhar Swami as a present, living Tirthankar.
• Chant softly or in mind, with shraddha (faith) and bhav (pure feeling).

Many Jains also first recite the Navkar Mantra, and then do Simandhar Swami name‑jaap.

You can read more about Simandhar Swami here