Don't get disheartened. I'd be surprised if most startup job pages had conversion rates much better than this.

The job market is white hot for programmers right now, and it's easy to get lost in all the noise.

When you're a startup, you're better off actively recruiting folks from local meetups, GitHub, HN, Twitter, and LinkedIn rather than expecting applicants to come to you.

So rather than optimize this, get out of the building and go meet some potential recruits.