Type a bash brace pattern and see exactly what the shell would expand it to — without running anything. Supports comma lists {a,b,c}, numeric ranges {1..10}, character ranges {a..z}, ranges with steps {0..20..2}, zero padding {001..010}, and arbitrary nesting {a,b{1..3},c}.
{a,b}{1,2} → a1 a2 b1 b2.{01..05} → 01 02 03 04 05.{a..f} → a b c d e f. They go in either direction.{10..1..2} → 10 8 6 4 2..., no comma), it is left intact like bash does.