There are several developer tools available as described below- 

One can use dev tools in the dev section to help test and debug during solidity and web3 dapp development. These tools include-

- EIP-712 signatures (there are a couple of templates available- including aave credit delegation signature)
- ERC-191 signatures
- gas convertor, byte conversion etc.
- Burner Wallet
- Merkle Tree Generator (using secure openzepplin libraries, provides easy debugging for whitelisting during a project launch)
- Deterministic Addresses (supports both create and create2 addresses)
- Checksum Formatter
- Transaction Decoder (also supports safe-multisig transaction data created using safe protocol-kit)

These can be accessed using the below link- 
https://zkblock.app/dev-tools

3 starter boilerplate for developing zk dapps (beginner friendly):
Walkthrough of how it works available here- https://medium.com/me/stats/post/6da73f6ef8ea
Link: https://boilerplate.zkblock.app/

Recently, also improved the EVM storage reader, currently available on PolygonMumbai- It allows you to read on-chain storage slots of deployed contracts, and provides more details about the smart contract. This helps investigate the contract storage deployed on chain during development and on mainnet.

This can be accessed -
Old Version-  https://evm.zkblock.app/
New Version - https://www.evmtools.xyz  

We are planning to migrate all the tools on the new domain (evmtools), and everything will also be available in a new format (to be disclosed) to make everything easily accessible for the developers. This will be our newer version of the platform and will be launched officially in Q3.