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Zcash improves through network upgrades: coordinated changes to the rules every node agrees on, each activated at a set block height. Every upgrade below has its own page that explains, in plain language, what it changed and why. New to Zcash? Read them in order, from Sprout to Ironwood.
For the visual story of how Zcash's privacy has evolved across these upgrades, see The Evolution of Privacy. This page is the index. That one is the timeline.
| Upgrade | Activation (UTC) | Block | Branch id | What it changed |
|---|---|---|---|---|
| Sprout | October 28, 2016 | genesis | 00000000 | The launch: the first shielded pool and zk-SNARK private transactions |
| Overwinter | June 26, 2018 | 347,500 | 5ba81b19 | Replay protection, transaction versioning, and expiry, so safe upgrades became possible |
| Sapling | October 29, 2018 | 419,200 | 76b809bb | Efficient shielded transactions, fast enough for phones and hardware wallets |
| Blossom | December 11, 2019 | 653,600 | 2bb40e60 | Faster blocks, about 75 seconds, and higher throughput |
| Heartwood | July 16, 2020 | 903,000 | f5b9230b | Shielded mining rewards and lighter clients (FlyClient) |
| Canopy | November 18, 2020 | 1,046,400 | e9ff75a6 | The Development Fund, the first halving, and winding down the Sprout pool |
| NU5 | May 31, 2022 | 1,687,104 | c2d6d0b4 | The Orchard pool on Halo 2 (no trusted setup), unified addresses, and v5 transactions |
| NU6 | November 23, 2024 | 2,726,400 | c8e71055 | The Deferred Dev Fund Lockbox and a new development funding split |
| NU6.1 | November 24, 2025 | 3,146,400 | 4dec4df0 | Community and coin-holder governance of that funding |
| NU6.2 | June 3, 2026 | 3,364,600 | 5437f330 | An emergency fix that corrected the Orchard circuit |
| Ironwood (NU6.3) | July 28, 2026 | 3,428,143 | 37a5165b | The Ironwood pool and a public turnstile that lets anyone audit the supply |
| NU7 (upcoming) | Testnet: 4 Oct 2026; Mainnet: targeted 5 Nov 2026 | Testnet: 4,465,026; Mainnet: 3,543,405 | 77190ad9 | 25-second blocks (ZIP 218), NSM fee recycling (ZIP 235+237), Sprout retirement (ZIP 2003) |
Dates are shown in UTC. Some dashboards show them in local time, which is the same block and the same moment. The fixed trigger for every upgrade is its activation block height, not the calendar date.
NU7 is live on public Testnet at height 4,465,026 (activated 4 October 2026). The Mainnet activation height is 3,543,405 (ZIP 259), targeted for 5 November 2026.
Scope (ZIP 259):
No new transaction format is introduced. Consensus branch ID: 0x77190ad9.
See the Evolution of Privacy timeline and ZIP 259 for full details. Forum timeline: NU7 Timeline.
