Blockcerts costs money to issue, right?

Feel free to answer on Bitcoin Stack Exchange:

I’m reading through this Github Repo from on how to issue digital certificates on the bitcoin blockchain.

What is confusing me is whether or not each issuing each digital certificate in this manner costs money.

On one hand, I’ve read through the high-level Blockcerts documentation and blogs and haven’t seen any reference to financial costs to issuing certificates on the bitcoin blockchain.

On the other hand, in the cert-issuer repo it notes in the “Transaction Structure” of “How Batch Issuing Works”, the issuer needs a minimal amount of Bitcoin to create the transaction. At the very least, this is a fixed cost.

Additionally, in the documentation ( we see:

Ensure you’ve transfered a small amount of coin to your issuing
address. Note that each certificate costs 12750 satoshi


Make sure you have enough BTC in your issuing address. ($0.08 USD)

So, it sounds like each certificate costs about $0.30 to issue? Just want to make sure I understand correctly.

(Please note, I am totally new to blockchain, so apologies if this is a dumb/obvious question).

Yes , each certificate will cost a certain amount of money . Depending on how much content each certificate will hold .

NO,It is not depended on how much content each certificate will hold, you can including as many as certificates you can but use one transaction, They use Merkle tree to solve this problem.

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I noticed that documentation was out of date. I issuing page and posted a response to StackExchange.

Ensure you’ve transferred sufficient funds to your issuing address to cover the transaction fee:
- The transaction fee is the same no matter the number of certificates in the batch
- The default transaction fee used by cert-issuer is 60,000 satoshis (~$1.50 USD, 7/3/2017)
- Because the transaction fee is a factor in confirmation time, you may decide to increase or decrease this value in the config file (read more about current transaction fee/latency estimates:


Dear Kim,

Thank you for your answers. They are always very helpful.

Could you possibly explain to me very briefly how the transaction fee is coming together? What are the components of these costs?

Greetings from Germany

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