Do you need a building permit?
Most answers online stop at “it depends on your city.” This site goes and reads the city's code, then tells you the actual cutoff — the height, the square footage, the section number it comes from.
Start with your state
What makes an answer here different
Every rule on this site is traced to a numbered section of a real ordinance, with a link to it. When the code doesn't say plainly, the page says so and hands you the section and the department's phone number instead of guessing. A confident wrong answer about permits is worse than an honest “we couldn't confirm this.”
Two examples of why the local detail matters: San Antonio exempts only minor repairs to a fence under six feet, while Austin, seventy-four miles away, exempts the fence itself up to seven feet. San Antonio allows a shed up to 300 square feet without a permit; Austin stops at 200. Neither number is the national default.