Verified claim · AI-ML · 90% confidence
Anthropic Claude Sonnet 4.5 publicly released on: 2025-09-29 by Anthropic — production model improvements over Sonnet 4 with extended-thinking + better coding.
Last verified 2026-05-16 · Methodology veritas-v0.1 · 599668ba56c91952
Structured fields
- Subject
- Anthropic Claude Sonnet 4.5
- Predicate
publicly_released_on- Object
- 2025-09-29 by Anthropic — production model improvements over Sonnet 4 with extended-thinking + better coding
- Confidence
- 90%
- Tags
- claude-sonnet-4-5 · anthropic · frontier-model · extended-thinking · released_on · 2025
Sources (2)
[1] official blog · Anthropic · 2025-09-29
Introducing Claude Sonnet 4.5“Claude Sonnet 4.5 is our most intelligent model in the Sonnet line, with significant improvements on coding, reasoning, and agentic capabilities.”
[2] docs · Anthropic · 2025-09-29
Anthropic Models — claude-sonnet-4-5
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Anthropic Claude Sonnet 4.5 publicly released on: 2025-09-29 by Anthropic — production model improvements over Sonnet 4 with extended-thinking + better coding. — SourceScore Claim 599668ba56c91952 (verified 2026-05-16). https://sourcescore.org/api/v1/claims/599668ba56c91952.jsonEmbed this claim
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Frequently asked questions
Is the claim "Anthropic Claude Sonnet 4.5 publicly released on: 2025-09-29 by Anthropic — production model improvements over Sonnet 4 with extended-thinking + better coding." verified?
Yes — SourceScore verified this claim with 90% confidence as of 2026-05-16. The verification uses 2 primary sources cross-referenced against the SourceScore methodology (version veritas-v0.1). Full source list + signed JSON envelope linked below.
What is the evidence for "Anthropic Claude Sonnet 4.5 publicly released on: 2025-09-29 by Anthropic — production model improvements over Sonnet 4 with extended-thinking + better coding."?
Evidence comes from 2 primary sources: Anthropic, Anthropic. Each source is listed below with verbatim excerpts and URLs. The signed JSON envelope at https://sourcescore.org/api/v1/claims/599668ba56c91952.json includes an HMAC-SHA256 signature for audit verification.
When was this claim last verified by SourceScore?
Last verified 2026-05-16 under methodology version veritas-v0.1. The signed JSON envelope is dated and cryptographically signed for audit trail. Re-verification cadence depends on the claim type and source freshness.
How can I cite this SourceScore claim in my code or article?
Fetch the signed JSON envelope from https://sourcescore.org/api/v1/claims/599668ba56c91952.json which includes the verbatim claim, primary sources, confidence, methodology version, last-verified date, and HMAC-SHA256 signature for audit. The CC-BY-4.0 license permits commercial use with attribution to SourceScore.
Use this claim in your code
Fetch this signed envelope from your application. The response includes the verbatim excerpt, primary source URLs, and an HMAC-SHA256 signature you can verify locally for audit trails.
cURL
curl https://sourcescore.org/api/v1/claims/599668ba56c91952.jsonJavaScript / TypeScript
const r = await fetch("https://sourcescore.org/api/v1/claims/599668ba56c91952.json");
const envelope = await r.json();
console.log(envelope.claim.statement);
// "Anthropic Claude Sonnet 4.5 publicly released on: 2025-09-29 by Anthropic — production model improvements over Sonnet 4 with extended-thinking + better coding."Python
import httpx
r = httpx.get("https://sourcescore.org/api/v1/claims/599668ba56c91952.json")
envelope = r.json()
print(envelope["claim"]["statement"])
# "Anthropic Claude Sonnet 4.5 publicly released on: 2025-09-29 by Anthropic — production model improvements over Sonnet 4 with extended-thinking + better coding."LangChain (retrieve-then-cite)
from langchain_core.tools import tool
import httpx
@tool
def get_anthropic_claude_sonnet_4_5_fact() -> dict:
"""Fetch the verified SourceScore claim for Anthropic Claude Sonnet 4.5."""
r = httpx.get("https://sourcescore.org/api/v1/claims/599668ba56c91952.json")
return r.json()