List of Retrosynthetic Analysis Tools

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1. Administrator Site Administrator Sep 7, 2026

   1. Traditional Classic Computational Tools (Rule- and Database-Based)
   These rely on curated reaction databases, expert-encoded rules, and literature/patent data for known routes and conditions.
   ToolDeveloper/SourceCore FeaturesPrimary UsesReaxysElsevierBuilt-in retrosynthesis module; massive literature + patent dataKnown-compound synthesis lookup; experimental step tracingSciFinder-nCAS (ACS)Retrosynthesis on the most comprehensive CAS reaction databaseLiterature route search; condition verification; supplier queriesSynthia (formerly Chematica)Merck/Sigma-Aldrich>100,000 hand-coded reaction rules; logical, highly interpretableComplex-molecule route design; industrial R&D; route optimizationLHASAAcademic/teachingClassic expert system using “strategic bond disconnection” rulesTeaching demonstrations; academic research

2. Administrator Site Administrator Sep 7, 2026

   2. AI / Deep-Learning Models (Single-Step & Multi-Step Planning)
   These treat retrosynthesis as a sequence-to-sequence or graph-based prediction task trained on large reaction datasets.
   
   Synthon (Insilico Medicine)
   2.6-billion-parameter LFM using root-aligned SMILES strategy; Top-1 accuracy 66.23–74.12 %.
   Main use: high-accuracy single-step retrosynthesis prediction.
   C3LM (academic)
   Chemistry-reasonableness-aware LLM trained on 45.6 million reactions with ChemCensor reward mechanism.
   Main uses: handling out-of-distribution data and complementing classical models.
   Molecular Transformer (IBM Research)
   Sequence-to-sequence translation task (product SMILES → reactant SMILES).
   Main uses: open benchmark model and rapid single-step bond-breaking validation.
   RxnFP (IBM Research)
   Same series as Molecular Transformer.
   Main uses: reaction fingerprint generation and retrosynthesis prediction.
   G2Gs (Graph-to-Graph) (academic)
   Graph neural network that predicts bond-breaking positions and generates reactants.
   Main use: molecule-graph-level retrosynthetic analysis.

3. Administrator Site Administrator Sep 7, 2026

   3. LLM-Driven Intelligent Agent Systems (Constraint-Aware & Automated)
   These combine large language models with external tools, real-time constraint checking, and (in some cases) laboratory automation.
   
   LARC (academic, frontier)
   First “Agent-as-a-Judge” LLM framework that evaluates constraints in real time.
   Main uses: avoiding toxic intermediates and hazardous reactions (72.9 % success rate, 3.6× faster).
   ChemCrow (academic)
   LLM connected to RDKit and other external chemistry software.
   Main uses: design–make–test closed loops and shortening R&D cycles.
   Organa (academic)
   Combines LLM with laboratory automation equipment.
   Main uses: automated experiment design and execution.
   GIT-Mol (academic)
   Multimodal model aligning SMILES, molecular graphs, 3-D coordinates, and natural language.
   Main uses: retrosynthesis + property prediction + literature Q&A.
   nach0 (academic)
   Multimodal model in the same family as GIT-Mol.
   Main use: comprehensive chemical information processing.

4. Administrator Site Administrator Sep 7, 2026

   4. Open-Source / Freely Available Platforms
   These support local deployment, customization, and academic use.
   
   ASKCOS (MIT)
   Based on Transformer and neural-network strategies; supports multi-step search.
   Main uses: academic research, local deployment, single-step and multi-step retrosynthesis.
   AIZynthFinder (AstraZeneca)
   Monte-Carlo tree search (MCTS) that can be combined with any single-step prediction model.
   Main uses: local deployment, secondary development, and multi-step route search.
   IBM RXN (IBM)
   Transformer model available after free registration.
   Main uses: retrosynthesis prediction and forward reaction prediction.
   SynthI (open community)
   RDKit-based and locally deployable.
   Main use: lightweight retrosynthetic analysis.
   RDChiral (open community)
   RDKit-based retrosynthetic template library.
   Main use: underlying engine for custom development.
   Chemy AI (third-party)
   No API barriers or usage limits; integrates multi-step retrosynthesis engines.
   Main uses: general workflows, structure parsing, and database scanning.

5. Administrator Site Administrator Sep 7, 2026

   5. Other Commercial / Third-Party Tools
   
   Spaya (Iktos)
   AI-driven with emphasis on synthesizability scoring and route ranking.
   Main uses: automated route generation and optimization.
   Pistachio (NextMove Software)
   Automatically extracts reaction data from patents and literature.
   Main use: data foundation for building retrosynthesis engines.
   ChemPlanner (Wiley)
   Built on the Wiley reaction database.
   Main use: multi-step route planning.
   Chemical.AI (Chinese vendor)
   AI synthesis planning.
   Main use: industrial-scale synthetic route design.
   Molecule.one (third-party)
   AI synthesis planning.
   Main use: large-scale route discovery.