NLP Lineage

5 February 2026 · Agents

GPT-5.3-Codex

GPT-5.3-Codex

OpenAI

Date
5 February 2026
What the date marks
Model release
Kind
Model
Organisation
OpenAI
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 (openai.com)

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

What it changed

Before it

Coding agents worked through the shell and the file system.

The problem

Some development work happens in browsers and GUIs that have no command-line equivalent.

What it introduced

A coding model that also drives a computer directly.

Why it matters

It merged the coding-agent and computer-use lines into one product.

What modern models inherit

Coding agents that are not limited to the terminal.

What came next

The GPT-5.4 and 5.5 releases continued the agentic push.

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

GPT-5.3-Codex has 46 documented ancestors across 11 chapters, reaching back to Recurrent networks in 1990. Showing its direct parents and the 18 turning points among them.

GPT-5.3-Codex has 46 documented ancestors across 11 chapters, reaching back to Recurrent networks in 1990. Showing all of them.

GPT-5.3-Codex has 66 recorded ancestors, including indirect ones, across 11 chapters, reaching back to Recurrent networks in 1990. Showing its direct parents and the 18 turning points among them.

GPT-5.3-Codex has 66 recorded ancestors, including indirect ones, across 11 chapters, reaching back to Recurrent networks in 1990. Showing all of them.

  1. 2026GPT-5.3-CodexThis milestone.
  2. 2025GPT-5.2GPT-5.3-Codex built directly on thisChapter 14. Where the threads meet now
  3. 2025GPT-5.1GPT-5.2 built directly on thisChapter 14. Where the threads meet now
  4. 2025GPT-5GPT-5.1 built directly on thisChapter 14. Where the threads meet now
  5. 2025o3 releasedGPT-5 built directly on thisChapter 12. Thinking longer
  6. 2024o3 announcedo3 released succeeded thisChapter 12. Thinking longer
  7. 2024o1 Turning pointo3 released built directly on thisChapter 12. Thinking longer
  8. 2024GPT-4oGPT-5 succeeded thisChapter 11. Seeing and hearing
  9. 2023GPT-4VGPT-4o built directly on thisChapter 11. Seeing and hearing
  10. 2023Function callingo3 released was influenced by thisChapter 13. Models that act
  11. 2023GPT-4 Turning pointGPT-4o built directly on thisChapter 7. The assistant goes public
  12. 2022GPT-3.5 Turning pointGPT-4 succeeded thisChapter 7. The assistant goes public
  13. 2022InstructGPT Turning pointGPT-4 built directly on thisChapter 6. Teaching models what people want
  14. 2022Chain of thought Turning pointo1 was influenced by thisChapter 12. Thinking longer
  15. 2021FLANInstructGPT was influenced by thisChapter 6. Teaching models what people want
  16. 2020RLHF for summarisation Turning pointInstructGPT built directly on thisChapter 6. Teaching models what people want
  17. 2020GPT-3 Turning pointChain of thought was influenced by this
    InstructGPT built directly on this
    GPT-3.5 built directly on this    Chapter 5. Scale becomes a science
  18. 2020Scaling laws Turning pointGPT-4 built directly on thisChapter 5. Scale becomes a science
  19. 2019T5 Turning pointFLAN was influenced by thisChapter 4. Pretrain once, use everywhere
  20. 2019C4 Turning pointT5 was influenced by thisChapter 4. Pretrain once, use everywhere
  21. 2019RLHF for LMsRLHF for summarisation built directly on thisChapter 6. Teaching models what people want
  22. 2019Sparse Transformer Turning pointGPT-3 built directly on thisChapter 4. Pretrain once, use everywhere
  23. 2019GPT-2 Turning pointScaling laws was influenced by thisChapter 4. Pretrain once, use everywhere
  24. 2019WebTextGPT-2 was influenced by thisChapter 4. Pretrain once, use everywhere
  25. 2018BERT Turning pointT5 was influenced by thisChapter 4. Pretrain once, use everywhere
  26. 2018SentencePieceT5 built directly on thisChapter 4. Pretrain once, use everywhere
  27. 2018GPT-1GPT-2 built directly on thisChapter 4. Pretrain once, use everywhere
  28. 2018ELMoBERT was influenced by thisChapter 4. Pretrain once, use everywhere
  29. 2018ULMFiTBERT was influenced by thisChapter 4. Pretrain once, use everywhere
  30. 2017CoVeELMo was influenced by thisChapter 3. Attention, then only attention
  31. 2017Transformer Turning pointScaling laws built directly on thisChapter 3. Attention, then only attention
  32. 2017RLHF originRLHF for summarisation built directly on thisChapter 6. Teaching models what people want
  33. 2016Layer normTransformer built directly on this
    GPT-2 built directly on this    Chapter 3. Attention, then only attention
  34. 2015Residual connectionsTransformer was influenced by thisChapter 3. Attention, then only attention
  35. 2015LM pretraining Turning pointGPT-1 was influenced by thisChapter 2. Words become vectors
  36. 2015BPE tokenizationGPT-2 built directly on thisChapter 2. Words become vectors
  37. 2015Luong attentionTransformer was influenced by thisChapter 3. Attention, then only attention
  38. 2014AdamTransformer was influenced by thisChapter 2. Words become vectors
  39. 2014GloVeELMo built directly on thisChapter 2. Words become vectors
  40. 2014Seq2seq Turning pointTransformer built directly on thisChapter 2. Words become vectors
  41. 2014Attention Turning pointTransformer built directly on thisChapter 3. Attention, then only attention
  42. 2014GRU / encoder-decoderAttention built directly on thisChapter 2. Words become vectors
  43. 2013word2vecELMo was influenced by thisChapter 2. Words become vectors
  44. 2011NLP from scratchELMo was influenced by thisChapter 1. Language as probability
  45. 2003Neural LMNLP from scratch was influenced by this
    word2vec was influenced by this    Chapter 1. Language as probability
  46. 1997LSTM Turning pointSeq2seq built directly on thisChapter 1. Language as probability
  47. 1990Recurrent networksLSTM was influenced by thisChapter 1. Language as probability
  1. 2026GPT-5.3-CodexThis milestone.
  2. 2025GPT-5.2GPT-5.3-Codex built directly on thisChapter 14. Where the threads meet now
  3. 2025GPT-5.1GPT-5.2 built directly on thisChapter 14. Where the threads meet now
  4. 2025GPT-5GPT-5.1 built directly on thisChapter 14. Where the threads meet now
  5. 2025o3 releasedGPT-5 built directly on thisChapter 12. Thinking longer
  6. 2024o3 announcedo3 released succeeded thisChapter 12. Thinking longer
  7. 2024Computer useGPT-5.3-Codex was influenced by this (indirect influence)Chapter 13. Models that act
  8. 2024o1 Turning pointo3 released built directly on thisChapter 12. Thinking longer
  9. 2024Test-time computeo3 announced was influenced by this (indirect influence)Chapter 12. Thinking longer
  10. 2024Claude 3.5 SonnetComputer use built directly on thisChapter 14. Where the threads meet now
  11. 2024GPT-4oGPT-5 succeeded thisChapter 11. Seeing and hearing
  12. 2024Claude 3Claude 3.5 Sonnet built directly on thisChapter 14. Where the threads meet now
  13. 2023GPT-4VComputer use was influenced by thisChapter 11. Seeing and hearing
  14. 2023Function callingComputer use was influenced by this (indirect influence)Chapter 13. Models that act
  15. 2023Process supervisiono1 was influenced by this (indirect influence)Chapter 12. Thinking longer
  16. 2023Tree of thoughtsTest-time compute was influenced by this (indirect influence)Chapter 12. Thinking longer
  17. 2023GPT-4 Turning pointGPT-4V built directly on thisChapter 7. The assistant goes public
  18. 2023ClaudeClaude 3 built directly on thisChapter 7. The assistant goes public
  19. 2023ToolformerFunction calling was influenced by this (indirect influence)Chapter 13. Models that act
  20. 2022Constitutional AIClaude 3 built directly on thisChapter 6. Teaching models what people want
  21. 2022GPT-3.5 Turning pointGPT-4 succeeded thisChapter 7. The assistant goes public
  22. 2022ReActFunction calling was influenced by this (indirect influence)Chapter 13. Models that act
  23. 2022WhisperGPT-4o was influenced by this (indirect influence)Chapter 11. Seeing and hearing
  24. 2022HH-RLHFConstitutional AI built directly on this
    Claude was influenced by this    Chapter 6. Teaching models what people want
  25. 2022STaRo1 was influenced by this (indirect influence)Chapter 12. Thinking longer
  26. 2022Self-consistencyTest-time compute built directly on thisChapter 12. Thinking longer
  27. 2022InstructGPT Turning pointGPT-4 built directly on thisChapter 6. Teaching models what people want
  28. 2022Chain of thought Turning pointReAct built directly on thisChapter 12. Thinking longer
  29. 2021WebGPTReAct was influenced by this
    Toolformer was influenced by this    Chapter 13. Models that act
  30. 2021HHH assistantHH-RLHF built directly on thisChapter 6. Teaching models what people want
  31. 2021FLANInstructGPT was influenced by thisChapter 6. Teaching models what people want
  32. 2021CLIPGPT-4V was influenced by this (indirect influence)Chapter 11. Seeing and hearing
  33. 2020Vision TransformerCLIP built directly on thisChapter 11. Seeing and hearing
  34. 2020RLHF for summarisation Turning pointInstructGPT built directly on this
    WebGPT built directly on this    Chapter 6. Teaching models what people want
  35. 2020GPT-3 Turning pointToolformer built directly on thisChapter 5. Scale becomes a science
  36. 2020Scaling laws Turning pointGPT-4 built directly on thisChapter 5. Scale becomes a science
  37. 2019T5 Turning pointFLAN was influenced by thisChapter 4. Pretrain once, use everywhere
  38. 2019C4 Turning pointT5 was influenced by thisChapter 4. Pretrain once, use everywhere
  39. 2019RLHF for LMsRLHF for summarisation built directly on thisChapter 6. Teaching models what people want
  40. 2019Sparse Transformer Turning pointGPT-3 built directly on thisChapter 4. Pretrain once, use everywhere
  41. 2019GPT-2 Turning pointCLIP built directly on thisChapter 4. Pretrain once, use everywhere
  42. 2019WebTextGPT-2 was influenced by thisChapter 4. Pretrain once, use everywhere
  43. 2019Transformer-XLSparse Transformer was influenced by this (indirect influence)Chapter 4. Pretrain once, use everywhere
  44. 2018BERT Turning pointVision Transformer was influenced by thisChapter 4. Pretrain once, use everywhere
  45. 2018SentencePieceT5 built directly on thisChapter 4. Pretrain once, use everywhere
  46. 2018GPT-1GPT-2 built directly on thisChapter 4. Pretrain once, use everywhere
  47. 2018ELMoBERT was influenced by this
    GPT-1 was influenced by this (indirect influence)    Chapter 4. Pretrain once, use everywhere
  48. 2018ULMFiTBERT was influenced by this
    GPT-1 was influenced by this (indirect influence)    Chapter 4. Pretrain once, use everywhere
  49. 2017CoVeELMo was influenced by thisChapter 3. Attention, then only attention
  50. 2017RLHF originConstitutional AI was influenced by thisChapter 6. Teaching models what people want
  51. 2017Transformer Turning pointGPT-2 built directly on this
    Scaling laws built directly on this
    Vision Transformer built directly on this    Chapter 3. Attention, then only attention
  52. 2017ConvS2STransformer was influenced by this (indirect influence)Chapter 3. Attention, then only attention
  53. 2016Layer normGPT-2 built directly on thisChapter 3. Attention, then only attention
  54. 2015Residual connectionsTransformer was influenced by thisChapter 3. Attention, then only attention
  55. 2015LM pretraining Turning pointBERT was influenced by this
    GPT-1 was influenced by this    Chapter 2. Words become vectors
  56. 2015BPE tokenizationGPT-2 built directly on thisChapter 2. Words become vectors
  57. 2015Luong attentionTransformer was influenced by thisChapter 3. Attention, then only attention
  58. 2014AdamTransformer was influenced by thisChapter 2. Words become vectors
  59. 2014GloVeELMo built directly on thisChapter 2. Words become vectors
  60. 2014Seq2seq Turning pointTransformer built directly on thisChapter 2. Words become vectors
  61. 2014Attention Turning pointTransformer built directly on thisChapter 3. Attention, then only attention
  62. 2014GRU / encoder-decoderAttention built directly on thisChapter 2. Words become vectors
  63. 2013word2vecELMo was influenced by thisChapter 2. Words become vectors
  64. 2011NLP from scratchELMo was influenced by thisChapter 1. Language as probability
  65. 2003Neural LMNLP from scratch was influenced by this
    word2vec was influenced by this    Chapter 1. Language as probability
  66. 1997LSTM Turning pointSeq2seq built directly on this
    ELMo built directly on this    Chapter 1. Language as probability
  67. 1990Recurrent networksLSTM was influenced by thisChapter 1. Language as probability

After: what it led to

GPT-5.3-Codex has 3 documented descendants across 1 chapter, reaching forward to GPT-5.6 Sol in 2026. Showing its direct descendants.

GPT-5.3-Codex has 3 documented descendants across 1 chapter, reaching forward to GPT-5.6 Sol in 2026. Showing all of them.

GPT-5.3-Codex has 3 recorded descendants, including indirect ones, across 1 chapter, reaching forward to GPT-5.6 Sol in 2026. Showing its direct descendants.

GPT-5.3-Codex has 3 recorded descendants, including indirect ones, across 1 chapter, reaching forward to GPT-5.6 Sol in 2026. Showing all of them.

  1. 2026GPT-5.3-CodexThis milestone.
  2. 2026GPT-5.4built directly on GPT-5.3-CodexChapter 14. Where the threads meet now
  3. 2026GPT-5.5built directly on GPT-5.4Chapter 14. Where the threads meet now
  4. 2026GPT-5.6 Solbuilt directly on GPT-5.5Chapter 14. Where the threads meet now
  1. 2026GPT-5.3-CodexThis milestone.
  2. 2026GPT-5.4built directly on GPT-5.3-CodexChapter 14. Where the threads meet now
  3. 2026GPT-5.5built directly on GPT-5.4Chapter 14. Where the threads meet now
  4. 2026GPT-5.6 Solbuilt directly on GPT-5.5Chapter 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