ChainBench · Flotapponnier · Aug 29, 2026 · Aug 29, 2026
@@ -0,0 +1,138 @@
+# OpenChainBench. Bench No 253
+
+slug: union-rpc
+number: "253"
+title: Fastest free Union RPC, live no-key endpoint latency
+seo_title: "Fastest free Union RPC 2026"
+seo_description: "{{best_name}} leads free Union RPC at {{best_p50}} (block height p50, 24h). 3 providers measured every 60s from 3 regions."
+subtitle: HTTP round-trip latency for Tendermint /status queries against every available public Union (union-1) endpoint, audited every 60 seconds from 3 regions.
+
+category: RPCs
+status: live
+metric: RPC latency
+unit: ms
+higher_is_better: false
+
+seo_intro: |
+  Union is a trust-minimised, zero-knowledge cross-chain protocol built on a custom Cosmos SDK chain (chain ID union-1). It enables secure interoperability between Cosmos, EVM, and other ecosystems via ZK proof-based consensus verification — no external validators or multisigs required. The chain uses the standard Tendermint RPC interface; block height is fetched via the /status endpoint. Public keyless RPC nodes are provided by Nodes.Guru, Stake And Relax, and High Stakes. Every provider was live-verified with consecutive block-height probes at launch.
+
+abstract: |
+  Per-chain member of the RPC latency cluster, extended to Union (union-1).
+  We measure the round-trip latency of a Tendermint /status query against
+  every available public Union endpoint that sustains continuous probing:
+  3 providers at launch, every 60 seconds, from us-east, eu-west and
+  Singapore. Each provider is probed via a GET /status request
+  from which the block number is extracted.
+  The harness classifies every response (ok / http_err / jsonrpc_err / stale / timeout)
+  with a Cosmos-scaled staleness gap (20 blocks, around 80 s at 4 s/block).
+  The cross-chain view lives on the parent rpc-capabilities benchmark;
+  this page is the Union-scoped answer with per-region breakdowns as
+  a first-class dimension.
+
+methodology:
+  - "Cadence: every 60 seconds per provider, from each of 3 probe regions (us-east Virginia, eu-west Amsterdam, sgp Singapore). Headline p50/p90/p99 aggregate across all 3 regions via Prometheus avg(quantile_over_time(...)); per-region breakdowns are first-class on this page via the region tabs."
+  - "Payload: GET /status. The result.sync_info.latest_block_height field (string-encoded integer) is extracted as the current block height."
+  - "Latency: client-side round-trip delta in milliseconds, exposed as both a gauge and a histogram (buckets 50 ms to 10 s), so percentiles are computed via Prometheus quantile_over_time over the last 24 hours."
+  - "Call-result classification: ok (parsable block height returned), http_err, jsonrpc_err, stale (block more than 20 behind the cross-provider tip), timeout."
+  - "This page is part of the per-chain RPC cluster derived from the cross-chain rpc-capabilities benchmark; the identical harness, cadence and exclusion rules apply on every chain."
+  - "Chain scope: every query on this page is pinned to chain=union. Provider coverage at launch: 3 endpoints (Nodes.Guru, Stake And Relax, High Stakes)."
+
+findings:
+  - "{{best_name}} leads free Union RPC at {{best_p50}} (Tendermint /status p50, 24h) across 3 measured providers."
+
+faq:
+  - q: "What is the fastest free Union RPC right now?"
+    a: "{{best_name}} currently leads at {{best_p50}} (Union block height p50 over the last 24h), measured against 3 providers probed every 60 seconds from us-east, eu-west and Singapore. The leaderboard re-sorts continuously against fresh Prometheus samples."
+  - q: "Which Union RPC endpoints work without an API key?"
+    a: "3 endpoints sustain continuous keyless probing at launch: Nodes.Guru (rpc-1.union.nodes.guru), Stake And Relax (union-rpc.stakeandrelax.net), and High Stakes (union-rpc.highstakes.ch). Every listed endpoint was live-verified before inclusion."
+  - q: "What is Union and why does its RPC latency matter?"
+    a: "Union is a ZK-based cross-chain interoperability protocol with a native Cosmos SDK chain (union-1). It connects blockchains without trusted intermediaries by verifying consensus proofs on-chain. Developers building cross-chain applications, bridges, or omnichain protocols on Union need reliable low-latency RPC access to query transactions, proofs, and chain state."
+  - q: "Does the fastest Union RPC change by region?"
+    a: "Often. Community validators like Nodes.Guru and High Stakes host in different datacentres. The region tabs re-scope every number to a single probe origin so you can pick the best endpoint for your user base."
+  - q: "What makes Union different from other cross-chain protocols?"
+    a: "Union replaces trusted validator sets and multisigs with ZK consensus proofs, making cross-chain message passing verifiable on-chain. This means no external trust assumptions — the security of the bridge reduces to the security of the underlying chains and ZK proof system."
+
+source: https://github.com/ChainBench/OpenChainBench/tree/main/harnesses/rpc-capabilities
+
+prometheus:
+  window: 24h
+  freshness_metric: rpc_latency_milliseconds
+
+rank_matrix_query: avg by (provider, region) (ocb:rpc_latency_milliseconds:p50_24h{chain="union"})
+
+dimensions:
+  region:
+    - { value: all,     label: All regions }
+    - { value: us-east, label: US-East }
+    - { value: eu-west, label: EU-West }
+    - { value: sgp,     label: Singapore }
+
+providers:
+  - slug: nodes-guru
+    name: Nodes.Guru
+    tag: Nodes.Guru public Union RPC, no API key required
+    formula: "50th percentile over 24h of client-side round-trip latency (ms) for a GET /status sent every 60s from 3 regions to rpc-1.union.nodes.guru."
+    queries:
+      p50: avg(ocb:rpc_latency_milliseconds:p50_24h{provider="nodes-guru", chain="union"})
+      p90: avg(ocb:rpc_latency_milliseconds:p90_24h{provider="nodes-guru", chain="union"})
+      p99: avg(ocb:rpc_latency_milliseconds:p99_24h{provider="nodes-guru", chain="union"})
+      mean: avg(ocb:rpc_latency_milliseconds:mean_24h{provider="nodes-guru", chain="union"})
+      success: sum(ocb:rpc_call:ok_rate_24h{provider="nodes-guru", chain="union"}) / sum(ocb:rpc_call:rate_24h{provider="nodes-guru", chain="union"})
+      sample_size: sum(ocb:rpc_call:increase_24h{provider="nodes-guru", chain="union"})
+      series: avg(avg_over_time(rpc_latency_milliseconds{provider="nodes-guru", chain="union"}[1h]))
+      regions:
+        - region: us-east
+          p50: avg(ocb:rpc_latency_milliseconds:p50_24h{provider="nodes-guru", chain="union", region="us-east"})
+          series: avg_over_time(rpc_latency_milliseconds{provider="nodes-guru", chain="union", region="us-east"}[1h])
+        - region: eu-west
+          p50: avg(ocb:rpc_latency_milliseconds:p50_24h{provider="nodes-guru", chain="union", region="eu-west"})
+          series: avg_over_time(rpc_latency_milliseconds{provider="nodes-guru", chain="union", region="eu-west"}[1h])
+        - region: ap-southeast
+          p50: avg(ocb:rpc_latency_milliseconds:p50_24h{provider="nodes-guru", chain="union", region="sgp"})
+          series: avg_over_time(rpc_latency_milliseconds{provider="nodes-guru", chain="union", region="sgp"}[1h])
+
+  - slug: stakeandrelax
+    name: Stake And Relax
+    tag: Stake And Relax public Union RPC, no API key required
+    formula: "50th percentile over 24h of client-side round-trip latency (ms) for a GET /status sent every 60s from 3 regions to union-rpc.stakeandrelax.net."
+    queries:
+      p50: avg(ocb:rpc_latency_milliseconds:p50_24h{provider="stakeandrelax", chain="union"})
+      p90: avg(ocb:rpc_latency_milliseconds:p90_24h{provider="stakeandrelax", chain="union"})
+      p99: avg(ocb:rpc_latency_milliseconds:p99_24h{provider="stakeandrelax", chain="union"})
+      mean: avg(ocb:rpc_latency_milliseconds:mean_24h{provider="stakeandrelax", chain="union"})
+      success: sum(ocb:rpc_call:ok_rate_24h{provider="stakeandrelax", chain="union"}) / sum(ocb:rpc_call:rate_24h{provider="stakeandrelax", chain="union"})
+      sample_size: sum(ocb:rpc_call:increase_24h{provider="stakeandrelax", chain="union"})
+      series: avg(avg_over_time(rpc_latency_milliseconds{provider="stakeandrelax", chain="union"}[1h]))
+      regions:
+        - region: us-east
+          p50: avg(ocb:rpc_latency_milliseconds:p50_24h{provider="stakeandrelax", chain="union", region="us-east"})
+          series: avg_over_time(rpc_latency_milliseconds{provider="stakeandrelax", chain="union", region="us-east"}[1h])
+        - region: eu-west
+          p50: avg(ocb:rpc_latency_milliseconds:p50_24h{provider="stakeandrelax", chain="union", region="eu-west"})
+          series: avg_over_time(rpc_latency_milliseconds{provider="stakeandrelax", chain="union", region="eu-west"}[1h])
+        - region: ap-southeast
+          p50: avg(ocb:rpc_latency_milliseconds:p50_24h{provider="stakeandrelax", chain="union", region="sgp"})
+          series: avg_over_time(rpc_latency_milliseconds{provider="stakeandrelax", chain="union", region="sgp"}[1h])
+
+  - slug: highstakes
+    name: High Stakes
+    tag: High Stakes public Union RPC, no API key required
+    formula: "50th percentile over 24h of client-side round-trip latency (ms) for a GET /status sent every 60s from 3 regions to union-rpc.highstakes.ch."
+    queries:
+      p50: avg(ocb:rpc_latency_milliseconds:p50_24h{provider="highstakes", chain="union"})
+      p90: avg(ocb:rpc_latency_milliseconds:p90_24h{provider="highstakes", chain="union"})
+      p99: avg(ocb:rpc_latency_milliseconds:p99_24h{provider="highstakes", chain="union"})
+      mean: avg(ocb:rpc_latency_milliseconds:mean_24h{provider="highstakes", chain="union"})
+      success: sum(ocb:rpc_call:ok_rate_24h{provider="highstakes", chain="union"}) / sum(ocb:rpc_call:rate_24h{provider="highstakes", chain="union"})
+      sample_size: sum(ocb:rpc_call:increase_24h{provider="highstakes", chain="union"})
+      series: avg(avg_over_time(rpc_latency_milliseconds{provider="highstakes", chain="union"}[1h]))
+      regions:
+        - region: us-east
+          p50: avg(ocb:rpc_latency_milliseconds:p50_24h{provider="highstakes", chain="union", region="us-east"})
+          series: avg_over_time(rpc_latency_milliseconds{provider="highstakes", chain="union", region="us-east"}[1h])
+        - region: eu-west
+          p50: avg(ocb:rpc_latency_milliseconds:p50_24h{provider="highstakes", chain="union", region="eu-west"})
+          series: avg_over_time(rpc_latency_milliseconds{provider="highstakes", chain="union", region="eu-west"}[1h])
+        - region: ap-southeast
+          p50: avg(ocb:rpc_latency_milliseconds:p50_24h{provider="highstakes", chain="union", region="sgp"})
+          series: avg_over_time(rpc_latency_milliseconds{provider="highstakes", chain="union", region="sgp"}[1h])
@@ -1693,6 +1693,17 @@ func chains() []Chain {
 				{Slug: "cosmos-directory", Name: "Cosmos Directory", URL: envDefault("RPC_URL_SENTINEL_COSMOSDIRECTORY", "https://rpc.cosmos.directory/sentinel")},
 			},
 		},
+		// 2026-08-29 wave-12. Union — Cosmos SDK (union-1), Tendermint /status. Nodes.Guru + Stake And Relax + High Stakes.
+		{
+			Slug: "union",
+			Name: "Union",
+			Kind: "cosmos",
+			Providers: []Provider{
+				{Slug: "nodes-guru", Name: "Nodes.Guru", URL: envDefault("RPC_URL_UNION_NODESGURU", "https://rpc-1.union.nodes.guru")},
+				{Slug: "stakeandrelax", Name: "Stake And Relax", URL: envDefault("RPC_URL_UNION_STAKEANDRELAX", "https://union-rpc.stakeandrelax.net")},
+				{Slug: "highstakes", Name: "High Stakes", URL: envDefault("RPC_URL_UNION_HIGHSTAKES", "https://union-rpc.highstakes.ch")},
+			},
+		},
 		// 2026-08-28 wave-11. Fetch.ai (FetchHub-4) — Cosmos SDK, Tendermint /status. Official + PublicNode + Cosmos Directory.
 		{
 			Slug: "fetchhub",

@@ -2619,6 +2619,26 @@ export const PROVIDER_REGISTRY: Record<string, ProviderRegistryEntry> = {
       "Fetch.ai official public Tendermint RPC node for the FetchHub-4 mainnet. Keyless endpoint maintained by the Fetch.ai / ASI Alliance team.",
     twitter: "@Fetch_ai",
   },
+
+  // ─── Union providers (bench 253) ─────────────────────────────────────
+  "nodes-guru": {
+    url: "https://nodes.guru",
+    description:
+      "Nodes.Guru community validator and public RPC operator. Runs keyless Tendermint RPC endpoints for multiple Cosmos SDK chains including Union.",
+    twitter: "@nodes_guru",
+  },
+  stakeandrelax: {
+    url: "https://stakeandrelax.net",
+    description:
+      "Stake And Relax community validator providing public keyless Tendermint RPC for Cosmos SDK chains including Union.",
+    twitter: "@StakeAndRelax",
+  },
+  highstakes: {
+    url: "https://highstakes.ch",
+    description:
+      "High Stakes Swiss validator and public RPC operator. Provides keyless Tendermint RPC endpoints for multiple Cosmos SDK chains including Union.",
+    twitter: "@HighStakesCH",
+  },
 };
 
 /**

@@ -173,11 +173,12 @@ const BRANDS: Record<string, Brand> = {
   acala:    { color: "#E40C5B" },             // acala red/pink (official brand)
   interlay: { color: "#1A3BDB" },             // interlay blue (official brand)
 
-  // ─── Cosmos SDK chains (benches 247, 250-252) ───
+  // ─── Cosmos SDK chains (benches 247, 250-253) ───
   babylon:   { color: "#F8811A" },             // babylon orange (official brand)
   chihuahua: { color: "#E05F2A" },             // chihuahua orange-red (official brand)
   sentinel:  { color: "#00C2FF" },             // sentinel cyan (official brand)
   fetchhub:  { color: "#3B2D8E" },             // fetch.ai deep purple (official brand)
+  union:     { color: "#6366F1" },             // union indigo (brand kit)
   "cosmos-directory": { color: "#1B1B2F", dark: true }, // cosmos directory dark navy
 
   // ─── Bitcoin Cash chain + providers (bench 244) ───

@@ -331,6 +331,7 @@ const RAW: Record<string, string> = {
   chihuahua: "/logos/chihuahua.svg",
   sentinel: "/logos/sentinel.svg",
   fetchhub: "/logos/fetchai.svg",
+  union: "/logos/union.svg",
   "cosmos-directory": "/logos/cosmos-directory.svg",
 
   // ─── Oracle deviation (bench 025) — additional brand logos ───