Chains & Infrastructure
Polygon PoS: Milestone Finality and Ethereum Checkpoints
Polygon PoS is a sidechain anchored to Ethereum by checkpoints, and its own docs say it is not a rollup. Bor produces blocks. Heimdall-v2 validates and posts checkpoints. Milestones finalize a transaction in 2 to 5 seconds. POL pays gas. A USDC transfer cost $0.00135 at current conditions on 11 September 2026.
| Fact | Value | As of | Source |
|---|---|---|---|
| Genesis block (Bor block 0) | 30 May 2020, 07:47:16 UTC, two-node identical | C-39 | |
| Architecture | Sidechain with Ethereum checkpoint anchoring, not a rollup | C-37 | |
| Milestone finality | 2 to 5 seconds, deterministic, chain-local | C-37 | |
| Ethereum anchoring | Checkpoints, on a governance-set cadence | C-37 | |
| Native token | POL, gas and staking, 1 to 1 from MATIC | C-37 | |
| Fee model | EIP-1559 since the London hard fork | C-37 | |
| Conditions USDC transfer fee | $0.00135, then $0.0013 on a second pull | C-39 | |
| Observed median USDC transfer fee | $0.0080, batch-inclusive | C-39 | |
| Stablecoins on chain (provider) | $3,106,225,722.60 | C-10 |
What Polygon PoS is
Polygon PoS is a two-layer network anchored to Ethereum. Its genesis, Bor block zero, carries a timestamp of 30 May 2020, 07:47:16 UTC [6]. Two independent providers returned it identically [6] [7]. The captured documentation states no public launch date. Genesis serves as the launch proxy here, stated as a proxy, under the same rule this library applies to Base.
The architecture, in its own words
The docs name the two layers. A consensus layer called Heimdall-v2. An execution layer called Bor [4]. Bor handles block production. Heimdall-v2 handles validation, checkpoint submission, and coordination with Ethereum [4]. Heimdall-v2 is built on Cosmos SDK and CometBFT. Bor is built on Go Ethereum [4]. Staking, checkpoint, and bridge contracts live on Ethereum mainnet [4].
Block production is selective. A single producer is selected from a small pool of eligible validators for each span [4].
Sidechain, not rollup
This is the load-bearing classification, and the docs carry it themselves. The PoS mechanism provides a partial mitigation for the data unavailability problem on Polygon sidechains, since checkpoint data is anchored to Ethereum [4]. The chain’s own documentation calls it a sidechain with checkpoint anchoring. It does not post per-transaction data to Ethereum the way a rollup does. The layer 1 versus layer 2 page holds the full structural comparison. This page keeps the classification visible and does not round it up.
What finality means here
Two mechanisms, two scopes [4].
Milestones are chain-local and deterministic. Since the Heimdall-v2 upgrade, deterministic finality arrives in 2 to 5 seconds, on 1 to 2 second Heimdall block times [4]. The rule: Heimdall looks for the longest common sequence of block hashes with two-thirds or more agreement among validators [4].
Checkpoints are the Ethereum-anchored leg. Checkpoints cover a contiguous range of Bor blocks, submitted to Ethereum mainnet [4]. The range length is a governance-set parameter, not a fixed cadence [4]. A transaction is finalized by a milestone well before the next checkpoint goes up [4]. The query standard is the finalized block tag [4].
Issuer overview figures travel with a label. The chain’s overview page states sub-5 second finality, 3,800 TPS, and a $0.002 average transaction cost [4]. Issuer-stated, context only, not measurements by this library.
The native token
POL is the native token of the Polygon ecosystem, replacing MATIC [4]. It serves as the gas and staking token [4]. The migration was a 1-to-1 conversion, with an initial POL supply of 10 billion matching MATIC at migration [4]. The docs quote a 2 percent per year emission schedule revision [4].
How fees work
EIP-1559 has applied since the London hard fork [4]. The base fee is network-determined and burned, calculated from how full the previous block was [4]. The priority fee is an optional tip offered to the validator [4]. The fee paid is base plus priority [4]. The issuer runs a documented gas oracle, the Polygon Gas Station V2 [4].
Fees, measured
The conditions metric, dated 11 September 2026. Median base fee of 247.229 gwei times 56,231 simple-transfer gas, which is 0.0139019373 POL, about $0.00135 [6] [9]. A second pull read 239.3 gwei base, about $0.0013 [7]. The simple-gas median was identical across three pulls, the tightest distribution in this library’s eight-chain set [6] [7].
The observed metric. Fifty sampled native-USDC transfers. The median paid was 0.0824742884 POL, about $0.0080 [6] [9]. A wider 90-transfer window the same session read about $0.0043 [6]. Batch share drives that spread, the same pattern other batch-heavy chains show.
The check legs. An independent node’s full re-pull agreed on the base fee to 0.27 percent [7]. The issuer’s live gas oracle read 246.47 gwei estimated base against the nodes’ 244.96 to 247.23 [5]. Three-way agreement on the parameter. One documentation note: the docs page embeds a stale gas-station payload with a 6 second block time. The live oracle reads 1.3333 seconds, and the live oracle is the cited figure [5].
The stablecoin economy
One provider’s chains table put all stablecoins on Polygon at $3,106,225,722.60 on 11 September 2026 [8]. Database-reported, that provider’s methodology.
The roster
Two issuer-listed tokens run natively on Polygon PoS. The USDC address is issuer-doc verbatim, from the Polygon PoS row of Circle’s current table, captured fresh on 11 September 2026 [1]. An explorer API confirmed both names at the cross-check date.
| Token | Address, as the issuer publishes it |
|---|---|
| USDC, Circle [1] | 0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359 |
| PYUSD, PayPal | 0x99aF3EeA856556646C98c8B9b2548Fe815240750 |
Provenance, stated. The PayPal row is an issuer-published address banked by this project’s token verification packs. Its on-chain holder count on this chain is thin. The mcap figure in the source report is chain-wide, and the gap is worth naming.
The absences and exclusions, dated. Tether’s protocols page contains zero mentions of Polygon [3]. Circle’s EURC table carries no Polygon row [2]. No banked Sky address rows exist for Polygon. And one scope rule: the historically dominant bridged USDC variant is out of roster scope. This library rosters issuer-native tokens only, and the fee legs above measured the native contract.
Where this page sits
The chains hub holds the other networks. The USDC page holds the token this chain carries at scale. The PYUSD page holds the second roster token. The layer 1 versus layer 2 page explains why this chain sits outside the rollup family. Every figure above carries its date.
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