It really all depends on
- if your putting in any money
- How much your salary will be (market rate or lower)?
- existing investors
- if they're revenue generating
- how long the companies be around

Essentially it's the risk profile of the company that you're coming into.

If it's an idea and your coming in at the ground level and not taking a salary the 50/50.

If it's been around for a while, no investors and some traction or revenue, you'll be paid below market rate, then maybe 3-10%

If it's making money, raised some capital and your a "normal" developer (not a super star) then 1%

The key is that you ask for the Cap Table to truly understand what % of the company the type + amount of shares they're inferring equates to.

10,000 shares doesn't mean much if they have 100M outstanding.

Also, all equity should be vested over 4 years, 1 year cliff.