I see that most of the pallets are annotated as #[frame_support::pallet], but some of them are #[frame_support::pallet(dev_mode)] and my question is what exactly means dev-mode in the context of the annotation/pallet? Does it (in any way) help for delivering source code of a pallet?

To answer that question, I was looking at the documentation and was looking at Substrate code per se, but did not found exact answer. Of course, I have some guesses, but only empty guesses.

2 Answers 2


Specifying pallet(dev_mode) allows you to place the pallet in development mode, you should only see it in pallets that are under development.

It relaxes a number of constraints, provides defaults for a number of things that are not super relevant when a pallet is under construction (including weights), and disables accidental production compilation of the pallet.

Bruno made a great explanation in this previous Stackexchange answer: What is Dev Mode? And how can I use it?.

And here you can see PR where it was introduce: Add pallet dev mode


Here is the answer to dev mode: https://paritytech.github.io/polkadot-sdk/master/frame_support/attr.pallet.html#dev-mode-palletdev_mode

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