How much earlier is first-shred than slotSubscribe?

slotSubscribe fires when the validator processes a slot; the first-shred signal fires when the first shred of the leader's broadcast arrives — before the block is even complete. The gap is typically a large fraction of the slot time (~400ms budget).

What does each event contain?

Slot number, the leader identity for the slot, and the arrival timestamp of the first shred. It is a heartbeat signal — for transaction contents use the pre-execution stream.

Which plan includes it?

First-Shred is a Business-plan stream ($499/mo). Pro users can use the pre-execution transaction stream, which carries transaction bodies with account filters.

First-Shred slot stream

Last updated: August 18, 2026

Why slot timing matters

On Solana, reaction time is measured against a ~400 ms slot budget. Systems that align work to slot boundaries — leader-aware transaction submission, latency measurement, MEV-sensitive strategies — gain the most from learning that a slot has started as early as physically possible. The first shred of a leader's broadcast is that earliest observable moment; waiting for slotSubscribe means waiting for processing that happens well after.

Connect

websocat "wss://triport.io/ws/sol-firstshred?api-key=<api-key>"
# event
{"slot": 361872041, "leader": "<validator-pubkey>", "ts": "..."}

Pairing with other streams

First-Shred tells you when; the pre-execution stream tells you what — transactions deshredded from the same shred flow. Together they form the lowest-latency view of Solana available on a flat subscription, with no per-GB traffic billing.

FAQ

How much earlier is first-shred than slotSubscribe?: slotSubscribe fires when the validator processes a slot; the first-shred signal fires when the first shred of the leader's broadcast arrives — before the block is even complete. The gap is typically a large fraction of the slot time (~400ms budget).
What does each event contain?: Slot number, the leader identity for the slot, and the arrival timestamp of the first shred. It is a heartbeat signal — for transaction contents use the pre-execution stream.
Which plan includes it?: First-Shred is a Business-plan stream ($499/mo). Pro users can use the pre-execution transaction stream, which carries transaction bodies with account filters.