Epoch node API - contract create endpoint


Hi everyone,

I am developing Java based platform which has to communicate with Epoch node running locally. I managed to get localnet (3 nodes) up and running and I can curl API endpoints as expected. Now I’m trying to deploy smart contract from Java. Now if I’m not mistaken, in order to do that I have to generate contract creation transaction, sign it (ed25519) and then POST it to /transactions endpoint. Before making those requests using Java, I wanted to test few API endpoints manually (using curl or any similar tool) and check what JSON models I have to use in request body and also what responses do I get. I have found api documentation here and I’m trying to make request on /debug/contracts/create but I don’t know exactly how to format all the fields in body of this request. Are there any examples of real request/response data somewhere?

Thanks for any help you can provide.


Hi Filip,

Here is more documentation about the Epoch API: https://github.com/aeternity/protocol/tree/master/epoch/api

We don’t have a Java SDK but it might be helpful to look at the python, javascript or go SDKs to see how they do it.

Hope this helps,



Thanks John. Resources were helpful and resolved some of my issues. I am still confused about one thing which I cannot find answer to. There are two fields in /debug/contracts/create request: “call_data” and “code”. (as can be seen in this link to apidoc) They are of type byte array. I have few questions regarding these params.

In the case of “call_data” I assume those are constructor values for smart contract. How do I encode these? How to encode empty constructor? And what in case of solidity contract?

For “code” param, I found on docs you linked that its value type is base58 encoded bytecode of compiled smart contract. So I tried exactly that, but with Ethereum bytecode. I compiled Solidity smart contract, base58 encoded its bytecode and put “cb_” prefix on encoded string. I also adjusted “vm_version” field to integer value 2 since my bytecode is actually Solidity contract to be executed on AEVM (according to documentation here). But still I get error response when making request: {“reason”:“Not byte array: code”} . Something is wrong with my encoding but I don’t know exactly what. I encode bytecode here.

I know the questions are specific but any info regarding these two params, or “cb_xxxx…” value type would be very valuable for me, I’m having no progress with this for some time now.


Hi there filip,

Have you read https://github.com/aeternity/protocol/blob/master/epoch/api/contract_api_usage.md which explains these calls in some detail?

There are only Sophia contracts on æternity. I have not tried to deploy ethereum bytecode from Soldity contracts to æternity, and have no idea if it works. https://contracts.aepps.com/ will compile and deploy Sophia code for you, have you tried it?

Let me know how you get on.




One more thing–you may be able to use the Swagger interface definition at sdk-edgenet.aepps.com/api with something like swagger-codegen (https://swagger.io/tools/swagger-codegen/) to generate the access code. I had bad experiences with swagger-codegen and Rust, but it may work better for Java.