I made a survey of Block Explorers for Zcash available on the web right now.* I hope it is valuable to the community as-is, and also can be extended if other community members want to offer links or updates.
ZCASH BLOCK EXPLORER DIRECTORY
MAINNET
Nighthawk, cacho. Pledged no trackers. ZCG Funded. Onion address available.
http://zcashfgzdzxwiy7yq74uejvo2ykppu4pzgioplcvdnpmc6gcu5k6vwyd.onion/
emersonian. ZCG funded. Fork of Nighthawk.
3xpl. Multi-coin multi-language. No ads. Fast. Onion address available. Hackable with sign-up (free for students and academics): Database dumps, PDF exports, JSON/Websocket API.
http://3xplor3rzajysy4j5fi3g3k27vivfcw75zjxdb2tg2wpz3i4cdiyhxyd.onion/
NowNodes. difficult without js. Free API key.
Trezor.
TESTNET
Nighthawk, cacho. Pledged no trackers. ZCG Funded. Onion address available.
http://zcashfgzdzxwiy7yq74uejvo2ykppu4pzgioplcvdnpmc6gcu5k6vwyd.onion/
pittmutt. needs js.
MEMPOOL
needs js. mempool only. cute! ପ(๑•ᴗ-๑)ଓ
BRIDGES
Near network. needs js, cloudflare.
https://nearblocks.io/token/zec.omft.near
Maya Protocol. needs js. doesn’t explore blocks.
NOT GREAT
needs js
needs js, charts and some info but not a full block explorer
so many scripts
https://blockexplorer.one/zcash/mainnet
https://blockexplorer.one/zcash/testnet
NOT FUNCTIONING
Nighthawk, cacho. server error when looking at blocks.
emersonian. has server errors when exploring blocks.
str4d.
https://explorer.testnet.z.cash/
Blockchair. block-level inspection appears broken. needs js. multi-coin multi-language. Onion address available.
http://blkchairbknpn73cfjhevhla7rkp4ed5gg2knctvv7it4lioy22defid.onion/
ERR_TOO_MANY_REDIRECTS
unknown
https://zcash.blockexplorer.com/
https://minergate.com/blockchain/zec/blocks
https://zcash.plutomonkey.com/
https://explorer.zcashfr.io/insight/
gambling page
does not currently support zec
*Shoutout to @dismad and @Edicksonjga who offered me some links.