this website is called "arweave app
   explorer": [1]https://explorer.arweave.co/
   can be hard to find those sometimes
   viewblock, a block explorer, is
   onchain: [2]https://wrqt7rptepcvuyxcu47ovrksdhpct3nb26vc3t653grfqj7g6hu
   a.arweave.net/tGE_xfMjxVpi4qc-6sVSGd4p7aHXqi3P3dmiWCfm8eg
   says the tip block is
   870708 lR94WAWPp07Ckz521Rem5q7P1rYEySgOERZKshYWsTzmcQAWZ3HUNgDTmjS8FSci

References

   1. https://explorer.arweave.co/
   2. https://wrqt7rptepcvuyxcu47ovrksdhpct3nb26vc3t653grfqj7g6hua.arweave.net/tGE_xfMjxVpi4qc-6sVSGd4p7aHXqi3P3dmiWCfm8eg