How to detect that full node is in sync (using jsonrpc)?

Question

I have full bitcoin node available through jsonrpc interface. How my app can detect if this node is in sync with the network?

Answer 1

Using the getblockchaininfo RPC command :

• if initialblockdownload is true, your node is currently syncing with the network for the first time.
• else :
  • if the headers field number is superior to the blocks field number, your node is catching up with the current state (likely after having been restarted)
  • else if the headers field number is equal to the blocks field number, your node is synced ! 🎉

Here is the current output of the command for me :

$ bitcoin-cli getblockchaininfo
{
  "chain": "main",
  "blocks": 634379,
  "headers": 634379,
  "bestblockhash": "000000000000000000136f1b78deeebc33a9b7b33d25c2e37f5446cb33b586fd",
  "difficulty": 13732352106018.34,
  "mediantime": 1591963775,
  "verificationprogress": 0.9999999385944023,
  "initialblockdownload": false,
  "chainwork": "0000000000000000000000000000000000000000104a35fae53a5b470d8e9524",
--snip--
}