To add to the other answers, it varies heavily by variety of vegetable. E.g. parsnip seeds, even when stored in airtight containers in the fridge, will rarely l

To add to the other answers, it varies heavily by variety of vegetable. E.g. parsnip seeds, even when stored in airtight containers in the fridge, will rarely last beyond a year, whereas tomato seed viability can easily exceed 10+ years. I planted some 5 year old tomato seeds this season and had near 100% germination.