Dear [Friend's Name],

I hope this letter finds you well. I am writing to invite you to my birthday party, which I am organizing because I want to celebrate this special day with my close friends like you. The party will be held on [Date] at [Time]. The venue is [Venue Address].

Your presence would mean a lot to me as we can catch up and create some wonderful memories together. I really hope you can make it.

Looking forward to seeing you soon.

Best Regards,
[Your Name]