I know of Oraclize. As discussed in this answer How does Oraclize handle the TLSnotary secret? by Jeff Coleman there are disadvantages, and he suggests using TLSNotary oneself is safer than trusting Oraclize.

I need to fetch data from third-party API's to get private data with a private API key. It's not public data like ETH price where I can use a network of oracles to fetch this for me (like MakerDAO).

I'm wondering how you prove the information you're inputting is not altered since you received it. Oraclize uses TLSNotary, does anybody have any idea how that actually works/how to implement? I went to https://tlsnotary.org/ but don't see an automated service one can use (there is a browser extension).

If not TLSNotary, has anybody heard/used a different method to prove the data is not corrupted? Thanks for any help or ideas!

1 Answer 1


You may want to check Chain-link, yet there is not a complete solution for this problem with the oracles. On option will be to create your own API and sign the responses such that you can then check then in your contract. As far as I know, the TLSNotary cannot be validated on-chain.

hope this helps.

  • Hey Jaime, thanks for sharing your thoughts! I've heard of ChainLink but I believe they aren't on main-net yet. In terms of my own API and signing it, it doesn't prove the data I received from the third-party API is the data I'm submitting. It just validates that I'm the one submitting it. Ah, so TLSNotary wouldn't be a solution anyway on-chain. If that's the case I can probably make the process transparent to check if we cheated but won't stop us from cheating, similar to TLSNotary. Thanks for the info! I'm upvoting this answer but am not accepting it (for now)
    – savard
    Mar 25, 2019 at 16:22

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