# Contract Library

[Contract Library](https://library.dedaub.com/) is a free contract-centered blockchain explorer created by [Dedaub](https://dedaub.com/). First released in 2018, Contract Library continuously decompiles and analyzes all deployed contracts for human inspection and offers a platform for exposing vulnerabilities. Contracts added to the Opera chain appear in the library almost immediately.

Contract Library offers users the ability to:

<table data-card-size="large" data-view="cards"><thead><tr><th></th></tr></thead><tbody><tr><td><strong>Examine contract code</strong> at all levels, including bytecode, decompiled representations, and source code, if available.</td></tr><tr><td><strong>Check token balances</strong> and allowances ‒ both as grantor and grantee ‒ for every contract and account.</td></tr><tr><td><strong>Read the values</strong> of storage locations of a contract.</td></tr><tr><td><strong>Find identical contracts</strong>, as well as similar public functions.</td></tr><tr><td><strong>Interact with a contract</strong> (“read/write contract”), even if it has no published source code.</td></tr><tr><td><strong>Decompile arbitrary bytecode</strong> ‒ for instance, to examine attack contracts or to see if high-level code is translated into gas-efficient sequences.</td></tr><tr><td><strong>Examine transaction traces</strong> and effects, filter past actions by function, and perform local debugging of transactions.</td></tr></tbody></table>

Contract Library’s debugger is orders of magnitude more scalable than alternatives on other networks, enabling debugging complex transactions within a reasonable amount of time. This is achieved by implementing an efficient model of the EVM to offload computation from the Web3 client.