At Blocklytics, we've been analysing smart contracts for over a year. It's about time we deployed some of our own! We're excited to share our custom implementation of an NFT to sell and manage digital advertising space.

We are exploring ways to monetise in order to devote more resources towards it. We are selling advertising space through FYI tokens.

The first use of FYI tokens are to control the promoted pool slot on the homepage of

Example of a Promoted Pool

Post Summary

This post explains why we built on top of the ERC-721 Non-Fungible Token Standard and explains some of the implementation details.

What are NFTs?

Non-fungible tokens are a set of unique tokens where each token has characteristics that make it unique from the other tokens.

While most tokens are fungible (every token is the same as every other token), ERC-721 tokens are all unique.Think of them like rare, one-of-a-kind collectables. –

New guarantees for advertisers

We've seen NFTs grow as a standard for selling digital art and in-game assets. We believe they are also well-suited for digital ads.

FYI Tokens give the current owner the right to display a promoted pool on the homepage. The key advantages to our implementation:

  • Fair, public price discovery. We are auctioning FYI tokens on OpenSea. OpenSea is an auction site for Ethereum assets that gives everyone an opportunity to participate and see a history of bids.
  • Ad schedules enforced by smart contract. We can only create one FYI token for any given time period. Scheduling conflicts and double-selling ads are not possible.
  • Public record of activity. Interactions with the FYI token are all recorded on-chain for anyone to review, including content proposals and approvals.
  • Resale rights. Just in case anything changes, you can resell or transfer the redemption rights.
  • Immutable terms and conditions. We put a reference to the terms and conditions on-chain. Anyone can verify the terms and conditions have not changed since publication.

Handling ad content with permissions displays ad content based on smart contract variables. The website reads content from the currently active token, based on a built-in scheduling mechanism.

FYI token holders are the only stakeholders allowed to propose ad content. We approve content and reserve the right to remove ad content. This permissioned system is described below.

  • Propose content. Only the token holder may propose content. New content may be proposed at any time to facilitate change requests.
  • Approve content. We can approve proposed content. Approved content displays on automatically.
  • Reset content. We can reset approved content (effectively hiding the ad) if necessary.

Automated scheduling

Each token has a fixed start and end date which determines when the approved content is displayed. No one can change these dates. We cannot double-schedule ads, even if a token has been demonstrably destroyed.

For the first FYI token, we chose an advertising duration of 2 weeks. It is possible to implement different durations and schedule gaps.


We look forward to feedback on our implementation of digital ads using smart contracts. You can reach us on Discord, Twitter or Email.


How do I redeem the token and advertise a pool? Visit If you get stuck, email us and we'll be happy to help.

What about advertisers who want to promote scams? We do not want to help promote scams. We reserve the right to remove a promoted pool at anytime. We will endeavour to refund affected token holder(s) subject to our discretion.

What's next? Ethereum business models are hard. We are fortunate to contribute to this field and trial a simple advertising primitive built on the shoulders of giants. We will be collecting feedback on the experiment and continuing to iterate.