NLP Lineage

24 November 2025 · Reasoning

Claude Opus 4.5

Claude Opus 4.5

Anthropic

Date
24 November 2025
What the date marks
Model release
Kind
Model
Organisation
Anthropic
Access
API only
Threads
In the guided tour
Chapter 13. Models that act
Learning phases
7. Agents

A milestone: 1 later milestone descends directly from it, and its descendants reach 2 of the 10 threads. How levels are decided

Figures quoted here are reported by the organisation that built it, not independently verified.

Read the primary source (anthropic.com)

Full summary in progress. Until then, this page shows the milestone's record from the research data.

What it changed

Before it

SWE-bench Verified scores had been climbing through the 70s all year.

The problem

Whether agents could reliably resolve most real issues was still open.

What it introduced

80.9% on SWE-bench Verified, the first model reported above 80, at a lower price than its predecessor.

Why it matters

The 80% mark was the year's psychological threshold for agentic coding. The figure is vendor-reported with its own scaffold.

What modern models inherit

Agentic coding as the headline capability measure.

What came next

The Claude 5 generation in 2026.

Before and after

The milestones it descends from, and the milestones that descend from it. Work developed alongside it is not counted. Weak links are left out unless you include them.

Before: where it came from

Claude Opus 4.5 has 49 documented ancestors across 10 chapters, reaching back to Recurrent networks in 1990. Showing its direct parents and the 18 turning points among them.

Claude Opus 4.5 has 49 documented ancestors across 10 chapters, reaching back to Recurrent networks in 1990. Showing all of them.

Claude Opus 4.5 has 53 recorded ancestors, including indirect ones, across 10 chapters, reaching back to Recurrent networks in 1990. Showing its direct parents and the 18 turning points among them.

Claude Opus 4.5 has 53 recorded ancestors, including indirect ones, across 10 chapters, reaching back to Recurrent networks in 1990. Showing all of them.

  1. 2025Claude Opus 4.5This milestone.
  2. 2025Claude Sonnet 4.5Claude Opus 4.5 built directly on thisChapter 13. Models that act
  3. 2025Claude 4Claude Sonnet 4.5 built directly on thisChapter 13. Models that act
  4. 2025Claude 3.7Claude 4 built directly on thisChapter 12. Thinking longer
  5. 2024o1 Turning pointClaude 3.7 was influenced by thisChapter 12. Thinking longer
  6. 2024Claude 3.5 SonnetClaude 3.7 built directly on thisChapter 14. Where the threads meet now
  7. 2024Claude 3Claude 4 succeeded thisChapter 14. Where the threads meet now
  8. 2023SWE-benchClaude Opus 4.5 was influenced by thisChapter 13. Models that act
  9. 2023GPT-4 Turning pointSWE-bench was influenced by thisChapter 7. The assistant goes public
  10. 2023ClaudeClaude 3 built directly on thisChapter 7. The assistant goes public
  11. 2022Constitutional AIClaude 3 built directly on thisChapter 6. Teaching models what people want
  12. 2022GPT-3.5 Turning pointGPT-4 succeeded thisChapter 7. The assistant goes public
  13. 2022HH-RLHFConstitutional AI built directly on this
    Claude was influenced by this    Chapter 6. Teaching models what people want
  14. 2022InstructGPT Turning pointGPT-4 built directly on thisChapter 6. Teaching models what people want
  15. 2022Chain of thought Turning pointo1 was influenced by this
    Constitutional AI was influenced by this    Chapter 12. Thinking longer
  16. 2021HHH assistantHH-RLHF built directly on thisChapter 6. Teaching models what people want
  17. 2021FLANInstructGPT was influenced by thisChapter 6. Teaching models what people want
  18. 2021Codex / HumanEvalSWE-bench built directly on thisChapter 13. Models that act
  19. 2020RLHF for summarisation Turning pointInstructGPT built directly on thisChapter 6. Teaching models what people want
  20. 2020GPT-3 Turning pointCodex / HumanEval built directly on thisChapter 5. Scale becomes a science
  21. 2020Scaling laws Turning pointGPT-4 built directly on thisChapter 5. Scale becomes a science
  22. 2019T5 Turning pointFLAN was influenced by thisChapter 4. Pretrain once, use everywhere
  23. 2019C4 Turning pointT5 was influenced by thisChapter 4. Pretrain once, use everywhere
  24. 2019RLHF for LMsRLHF for summarisation built directly on thisChapter 6. Teaching models what people want
  25. 2019Sparse Transformer Turning pointGPT-3 built directly on thisChapter 4. Pretrain once, use everywhere
  26. 2019GPT-2 Turning pointScaling laws was influenced by this
    GPT-3 built directly on this    Chapter 4. Pretrain once, use everywhere
  27. 2019WebTextGPT-2 was influenced by thisChapter 4. Pretrain once, use everywhere
  28. 2018BERT Turning pointT5 was influenced by thisChapter 4. Pretrain once, use everywhere
  29. 2018SentencePieceT5 built directly on thisChapter 4. Pretrain once, use everywhere
  30. 2018GPT-1GPT-2 built directly on thisChapter 4. Pretrain once, use everywhere
  31. 2018ELMoBERT was influenced by thisChapter 4. Pretrain once, use everywhere
  32. 2018ULMFiTBERT was influenced by thisChapter 4. Pretrain once, use everywhere
  33. 2017CoVeELMo was influenced by thisChapter 3. Attention, then only attention
  34. 2017Transformer Turning pointScaling laws built directly on thisChapter 3. Attention, then only attention
  35. 2017RLHF originRLHF for summarisation built directly on this
    Constitutional AI was influenced by this    Chapter 6. Teaching models what people want
  36. 2016Layer normTransformer built directly on this
    GPT-2 built directly on this    Chapter 3. Attention, then only attention
  37. 2015Residual connectionsTransformer was influenced by thisChapter 3. Attention, then only attention
  38. 2015LM pretraining Turning pointGPT-1 was influenced by thisChapter 2. Words become vectors
  39. 2015BPE tokenizationGPT-2 built directly on thisChapter 2. Words become vectors
  40. 2015Luong attentionTransformer was influenced by thisChapter 3. Attention, then only attention
  41. 2014AdamTransformer was influenced by thisChapter 2. Words become vectors
  42. 2014GloVeELMo built directly on thisChapter 2. Words become vectors
  43. 2014Seq2seq Turning pointTransformer built directly on thisChapter 2. Words become vectors
  44. 2014Attention Turning pointTransformer built directly on thisChapter 3. Attention, then only attention
  45. 2014GRU / encoder-decoderAttention built directly on thisChapter 2. Words become vectors
  46. 2013word2vecELMo was influenced by thisChapter 2. Words become vectors
  47. 2011NLP from scratchELMo was influenced by thisChapter 1. Language as probability
  48. 2003Neural LMNLP from scratch was influenced by this
    word2vec was influenced by this    Chapter 1. Language as probability
  49. 1997LSTM Turning pointSeq2seq built directly on thisChapter 1. Language as probability
  50. 1990Recurrent networksLSTM was influenced by thisChapter 1. Language as probability
  1. 2025Claude Opus 4.5This milestone.
  2. 2025Claude Sonnet 4.5Claude Opus 4.5 built directly on thisChapter 13. Models that act
  3. 2025Claude 4Claude Sonnet 4.5 built directly on thisChapter 13. Models that act
  4. 2025Claude 3.7Claude 4 built directly on thisChapter 12. Thinking longer
  5. 2024o1 Turning pointClaude 3.7 was influenced by thisChapter 12. Thinking longer
  6. 2024Claude 3.5 SonnetClaude 3.7 built directly on thisChapter 14. Where the threads meet now
  7. 2024Claude 3Claude 4 succeeded thisChapter 14. Where the threads meet now
  8. 2023SWE-benchClaude Opus 4.5 was influenced by thisChapter 13. Models that act
  9. 2023Process supervisiono1 was influenced by this (indirect influence)Chapter 12. Thinking longer
  10. 2023GPT-4 Turning pointSWE-bench was influenced by thisChapter 7. The assistant goes public
  11. 2023ClaudeClaude 3 built directly on thisChapter 7. The assistant goes public
  12. 2022Constitutional AIClaude 3 built directly on thisChapter 6. Teaching models what people want
  13. 2022GPT-3.5 Turning pointGPT-4 succeeded thisChapter 7. The assistant goes public
  14. 2022HH-RLHFConstitutional AI built directly on this
    Claude was influenced by this    Chapter 6. Teaching models what people want
  15. 2022STaRo1 was influenced by this (indirect influence)Chapter 12. Thinking longer
  16. 2022InstructGPT Turning pointGPT-4 built directly on thisChapter 6. Teaching models what people want
  17. 2022Chain of thought Turning pointo1 was influenced by this
    Constitutional AI was influenced by this    Chapter 12. Thinking longer
  18. 2021HHH assistantHH-RLHF built directly on thisChapter 6. Teaching models what people want
  19. 2021FLANInstructGPT was influenced by thisChapter 6. Teaching models what people want
  20. 2021Codex / HumanEvalSWE-bench built directly on thisChapter 13. Models that act
  21. 2020RLHF for summarisation Turning pointInstructGPT built directly on thisChapter 6. Teaching models what people want
  22. 2020GPT-3 Turning pointCodex / HumanEval built directly on thisChapter 5. Scale becomes a science
  23. 2020Scaling laws Turning pointGPT-4 built directly on thisChapter 5. Scale becomes a science
  24. 2019T5 Turning pointFLAN was influenced by thisChapter 4. Pretrain once, use everywhere
  25. 2019C4 Turning pointT5 was influenced by thisChapter 4. Pretrain once, use everywhere
  26. 2019RLHF for LMsRLHF for summarisation built directly on thisChapter 6. Teaching models what people want
  27. 2019Sparse Transformer Turning pointGPT-3 built directly on thisChapter 4. Pretrain once, use everywhere
  28. 2019GPT-2 Turning pointScaling laws was influenced by this
    GPT-3 built directly on this    Chapter 4. Pretrain once, use everywhere
  29. 2019WebTextGPT-2 was influenced by thisChapter 4. Pretrain once, use everywhere
  30. 2019Transformer-XLSparse Transformer was influenced by this (indirect influence)Chapter 4. Pretrain once, use everywhere
  31. 2018BERT Turning pointT5 was influenced by thisChapter 4. Pretrain once, use everywhere
  32. 2018SentencePieceT5 built directly on thisChapter 4. Pretrain once, use everywhere
  33. 2018GPT-1GPT-2 built directly on thisChapter 4. Pretrain once, use everywhere
  34. 2018ELMoGPT-1 was influenced by this (indirect influence)Chapter 4. Pretrain once, use everywhere
  35. 2018ULMFiTGPT-1 was influenced by this (indirect influence)Chapter 4. Pretrain once, use everywhere
  36. 2017CoVeELMo was influenced by thisChapter 3. Attention, then only attention
  37. 2017Transformer Turning pointScaling laws built directly on thisChapter 3. Attention, then only attention
  38. 2017RLHF originRLHF for summarisation built directly on this
    o1 was influenced by this (indirect influence)
    Constitutional AI was influenced by this    Chapter 6. Teaching models what people want
  39. 2017ConvS2STransformer was influenced by this (indirect influence)Chapter 3. Attention, then only attention
  40. 2016Layer normTransformer built directly on this
    GPT-2 built directly on this    Chapter 3. Attention, then only attention
  41. 2015Residual connectionsTransformer was influenced by thisChapter 3. Attention, then only attention
  42. 2015LM pretraining Turning pointGPT-1 was influenced by thisChapter 2. Words become vectors
  43. 2015BPE tokenizationGPT-2 built directly on thisChapter 2. Words become vectors
  44. 2015Luong attentionTransformer was influenced by thisChapter 3. Attention, then only attention
  45. 2014AdamTransformer was influenced by thisChapter 2. Words become vectors
  46. 2014GloVeELMo built directly on thisChapter 2. Words become vectors
  47. 2014Seq2seq Turning pointTransformer built directly on thisChapter 2. Words become vectors
  48. 2014Attention Turning pointTransformer built directly on thisChapter 3. Attention, then only attention
  49. 2014GRU / encoder-decoderAttention built directly on thisChapter 2. Words become vectors
  50. 2013word2vecELMo was influenced by thisChapter 2. Words become vectors
  51. 2011NLP from scratchELMo was influenced by thisChapter 1. Language as probability
  52. 2003Neural LMNLP from scratch was influenced by this
    word2vec was influenced by this    Chapter 1. Language as probability
  53. 1997LSTM Turning pointSeq2seq built directly on thisChapter 1. Language as probability
  54. 1990Recurrent networksLSTM was influenced by thisChapter 1. Language as probability

After: what it led to

Claude Opus 4.5 has 6 documented descendants across 1 chapter, reaching forward to Claude Opus 5.5 in 2026. Showing its direct descendants.

Claude Opus 4.5 has 6 documented descendants across 1 chapter, reaching forward to Claude Opus 5.5 in 2026. Showing all of them.

Claude Opus 4.5 has 6 recorded descendants, including indirect ones, across 1 chapter, reaching forward to Claude Opus 5.5 in 2026. Showing its direct descendants.

Claude Opus 4.5 has 6 recorded descendants, including indirect ones, across 1 chapter, reaching forward to Claude Opus 5.5 in 2026. Showing all of them.

  1. 2025Claude Opus 4.5This milestone.
  2. 2026Claude Opus 4.6built directly on Claude Opus 4.5Chapter 14. Where the threads meet now
  3. 2026Claude Opus 4.7built directly on Claude Opus 4.6Chapter 14. Where the threads meet now
  4. 2026Claude Opus 4.8built directly on Claude Opus 4.7Chapter 14. Where the threads meet now
  5. 2026Claude Sonnet 5succeeded Claude Opus 4.8Chapter 14. Where the threads meet now
  6. 2026Claude Opus 5succeeded Claude Opus 4.8Chapter 14. Where the threads meet now
  7. 2026Claude Opus 5.5built directly on Claude Opus 5Chapter 14. Where the threads meet now
  1. 2025Claude Opus 4.5This milestone.
  2. 2026Claude Opus 4.6built directly on Claude Opus 4.5Chapter 14. Where the threads meet now
  3. 2026Claude Opus 4.7built directly on Claude Opus 4.6Chapter 14. Where the threads meet now
  4. 2026Claude Opus 4.8built directly on Claude Opus 4.7Chapter 14. Where the threads meet now
  5. 2026Claude Sonnet 5succeeded Claude Opus 4.8Chapter 14. Where the threads meet now
  6. 2026Claude Opus 5succeeded Claude Opus 4.8Chapter 14. Where the threads meet now
  7. 2026Claude Opus 5.5built directly on Claude Opus 5Chapter 14. Where the threads meet now

Direct links and their sources

Where it came from

Built directly on

Influenced by

What it led to

Built on directly by