Anthropic API: Opus 5.5 launches, replaces Opus 5 as flagship
What happened
Between the Sep 21, 2026 and Sep 28, 2026 captures of Anthropic's pricing page, Pulse recorded one change: Opus 5.5 ("Daily driver for agentic coding and enterprise work") launched at $4/MTok input, $20/MTok output (cache read $0.20, write $5.00), replacing Opus 5 as the flagship model; Opus 5 moved to Legacy Models at its original $5/$25 pricing. In detail: New flagship model Opus 5.5 ("Daily driver for agentic coding and enterprise work") launched at $4/MTok input, $20/MTok output, replacing Opus 5; Opus 5 moved to Legacy models at its original $5/$25 pricing. Pulse files it as a product change (feature added). Pulse's latest capture (Nov 9, 2026) lists Haiku 4.5 at $5 per MTok output + $1.25 per MTok cache write, Sonnet 5 at $2 per MTok input + $10 per MTok output, Opus 5 at $6.25 per MTok cache write + $0.50 per MTok cache read, Fable 5 at $12.50 per MTok cache write + $1 per MTok cache read and Opus 4.8 at $6.25 per MTok cache write + $5 per MTok input.
It lands 101 days after Anthropic's previous change, "Anthropic API shifts Opus 4.8 focus to enterprise agentic coding" (Jun 19, 2026). Anthropic has been tracked since 2024-11-17.
In the same window Microsoft, OpenAI, Google, Scale and X also changed their AI & Machine Learning pricing pages. Those moves are listed further down, and the Pulse Agent can compare them side by side.
- Feature addedOpus 5.5FeatureNot listed$4/MTok
| Plan | Field | Before | After | Change |
|---|---|---|---|---|
| Opus 5.5 | Feature | Not listed | $4/MTok | Feature added |
Values as written on Anthropic's public pricing page in the two captures Pulse compared; where the page states no number, the cells give the wording before and after.
Evidence
The two captures Pulse comparedFull-page captures of Anthropic's pricing page (anthropic.com) from Sep 21, 2026 and Sep 28, 2026; the change is marked near the top of the page, where "Not listed" becomes "$4/MTok".
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The two full-page captures with this change marked up are free with an account.
Anthropic, the last 90 days
Full historyDates are the day each change was detected, Eastern time.
- Oct 11, 2026Price decreaseAnthropic API launches Haiku 5.5 at $0.10/$0.50 per MTok, Haiku 4.5 goes Legacy
- Oct 8, 2026Price decreaseAnthropic API launches Haiku 5.5 at $0.10/$0.50, halves Sonnet 5.5 cache reads
- Sep 27, 2026Feature addedAnthropic API: Opus 5.5 launches, replaces Opus 5 as flagship This change
- Jul 2, 2026PackagingAnthropic API: Fast mode for Opus 4.8 + Managed Agents pricing added
Across AI & Machine Learning in the same window
All AI & Machine Learning changes- MicrosoftSep 28Microsoft Speech: batch enhanced-feature no-extra-charge note removed
- OpenAISep 25OpenAI refreshes plan taglines with benefit-led copy, prices unchanged
- GoogleSep 7Google Workspace: promo discount cut from 50% to 30%/20% off
- ScaleAug 28Scale rebrands GenAI Platform to GenAI Portfolio; no pricing or feature changes
- XAug 24X drops grok-4.5, adds Imagine image/video models and free Playground perk
Questions about this change
Did Anthropic raise prices in September 2026?
No list-price increase was recorded between Sep 21, 2026 and Sep 28, 2026 UTC. The change Pulse detected was a product change: feature added.
What changed on Anthropic's pricing page between Sep 21, 2026 and Sep 28, 2026 UTC?
Opus 5.5 feature: Not listed → $4/MTok. Pulse compared the captures it took on Sep 21, 2026 and Sep 28, 2026 UTC; the before/after table above lists each item as written on the page.
How often does Anthropic change its pricing?
Pulse recorded 0 other pricing-page changes for Anthropic in the 90 days before this one; the previous change was "Anthropic API shifts Opus 4.8 focus to enterprise agentic coding" on Jun 19, 2026; Anthropic has been tracked since 2024-11-17.