Compound Discoverer 3.5 — Full Review, License & Download Guide (2026)

If you work in metabolomics, environmental analysis, pharmaceutical research, or any field that demands confident small-molecule identification from high-resolution mass spectrometry data, there is one name that consistently stands at the forefront of analytical software: Thermo Scientific Compound Discoverer. The release of version 3.5 — which arrived in November 2025 and has since been extended with additional updates into 2026 — represents a significant leap forward for the platform. This guide covers everything from the core architecture of the software to new features in 2026, license models, and how to approach the download and activation process.

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What Is Compound Discoverer 3.5?

Compound Discoverer 3.5 (often written as CD 3.5) is a dedicated data analysis application developed by Thermo Fisher Scientific under the Thermo Scientific brand. It is purpose-built for processing high-resolution accurate-mass (HRAM) data generated primarily by Orbitrap-based mass spectrometers, such as the Q Exactive series, Exploris family, and Orbitrap Astral instruments, though it also supports GC-Orbitrap data with a dedicated GC/EI workflow module.

The core mission of the software is to help researchers move from raw instrument data to confident compound identification as fast as possible — without needing to chain together multiple disconnected tools or export data through fragile spreadsheet pipelines. Everything from peak detection, retention time alignment, gap filling, statistical comparison, spectral library search, in-silico fragmentation scoring, pathway mapping, and report generation happens inside one integrated environment.

Version 3.5 was officially released on November 14, 2025, with additional capability updates — including the SIRIUS integration and Annotation Confidence Scoring — following in late 2025 and early 2026. It is currently the most feature-rich version of the software available, and it forms the basis of this review.

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Who Uses Compound Discoverer 3.5?

The software is designed for a wide range of analytical disciplines. Its primary user base spans academic and industrial research labs, but it is equally well-suited to regulated industry environments. Specific application areas include:

• Untargeted and targeted metabolomics — the software’s original core application. Researchers studying disease biomarkers, plant secondary metabolites, gut microbiome chemistry, or nutritional biochemistry rely on CD 3.5 to identify thousands of features per sample.
• PFAS (per- and polyfluoroalkyl substances) analysis — a rapidly growing regulatory area. CD 3.5 introduced dedicated PFAS tools that are described in detail below.
• Drug metabolism and impurity identification (DMPK) — pharmaceutical and biotech labs use CD to track metabolite formation, structural elucidation of impurities, and forced-degradation studies.
• Food safety and environmental monitoring — screening for pesticide residues, mycotoxins, industrial contaminants, and emerging pollutants in complex matrices like soil, water, food, and feed.
• Extractables and leachables (E&L) — a niche but important compliance-driven workflow in medical device and pharmaceutical packaging analysis.
• Forensic and clinical toxicology — identifying unknown drugs, metabolites, and toxic compounds in biological samples.
• Lipidomics — enabled by the integrated LipidSearch node (introduced in v3.4 and now fully embedded in v3.5).

This breadth of coverage is a major reason why a Compound Discoverer license is considered a high-value investment in analytical laboratories worldwide.

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Core Architecture: Node-Based Workflows

The foundation of Compound Discoverer’s power is its node-based workflow engine. Rather than applying a fixed linear processing pipeline to every dataset, the software lets users assemble modular processing chains from individual algorithm blocks called nodes. Each node performs a specific operation — detecting chromatographic peaks, aligning retention times across samples, assigning molecular formulas, querying an external database, applying statistical tests, or generating a visualization.

Nodes connect together in a directed graph, and the user can drag, drop, and rearrange them using the workflow editor. This means a simple screening study requires only a handful of nodes, while a sophisticated multi-group metabolomics study with isotope labeling, pathway mapping, and multivariate statistics can be built by extending the same base workflow. The approach scales from simple to very complex without forcing the user into a rigid interface designed for only one application type.

Workflow templates are included out of the box for the most common scenarios, so new users are not faced with a blank canvas. These templates cover untargeted metabolomics, targeted metabolomics, PFAS analysis, drug metabolism, lipidomics, environmental screening, stable isotope labeling (flux analysis), and GC/EI-based workflows, among others. Templates can be saved, shared across a team, and versioned over time.

Advanced users can extend the platform further by writing custom nodes using Python (via the Scripting node), providing virtually unlimited extensibility for specialized research requirements.

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Compound Identification: Databases and Libraries

Identifying an unknown compound from a mass spectrum requires checking the observed data against reference information. CD 3.5 integrates directly with multiple identification resources:

mzCloud

Thermo Fisher’s own curated MS/MS spectral library, mzCloud, is the primary identification resource. It uses a tree-based spectral matching approach (MSn trees) rather than simple head-to-tail dot-product matching, which makes it significantly more robust for data-dependent acquisition (DDA) and data-independent acquisition (DIA) data. CD 3.5 uses mzCloud 2.0, which delivers improved compound identification accuracy and expanded compound coverage. An mzCloud account is required for online searching, but offline local spectral libraries are also supported.

ChemSpider and BioCyc

For broader chemical structure searches beyond spectral matching, CD 3.5 queries ChemSpider (a large chemical structure database maintained by the Royal Society of Chemistry) and BioCyc (a biochemical pathway and metabolite database). These resources help resolve structural candidates when no matching spectrum is available in the library.

mzVault and Custom Mass Lists

Local spectral libraries created with Thermo Scientific’s mzVault software can be searched directly. Custom mass lists in text or spreadsheet format — useful for targeted screening campaigns — can also be imported and used as reference data within a workflow.

mzLogic

This algorithm ranks chemical database hits by comparing predicted fragmentation patterns to observed MS/MS spectra, adding a layer of structural plausibility scoring on top of database search results. It dramatically improves the signal-to-noise of candidate lists, especially when multiple structural isomers are returned by a formula-based database query.

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New Features in Compound Discoverer 3.5 (2025–2026)

The 3.5 release delivered a focused set of highly practical improvements rather than sweeping architectural changes. The updates address real pain points reported by the user community and extend the software’s capabilities into emerging regulatory and scientific areas.

Enhanced FISh Scoring (In-Silico Fragmentation)

FISh (Fragmentation In-Silico for Scoring) is CD’s in-silico fragmentation engine. It generates predicted fragment ion series for candidate structures and scores how well those predictions match experimental MS/MS data. In version 3.5, FISh received a new algorithm that provides significantly improved coverage for negative ionization mode fragmentation — a historically weaker area compared to positive mode — as well as notably faster computation speeds. For researchers working in environmental chemistry, lipidomics, and metabolomics in negative ion mode, this is a meaningful practical improvement.

PFAS Scoring Node and PFAS Plot

Per- and polyfluoroalkyl substances have moved from academic curiosity to urgent regulatory concern globally. CD 3.5 introduces a dedicated PFAS Scoring node that applies specialized scoring criteria to flag and prioritize PFAS candidates in untargeted datasets. Complementing this is the new PFAS Plot, which visualizes the normalized mass defect (MD/C) versus normalized mass (m/C) for detected features — a chemical space representation uniquely informative for fluorinated compounds. A CF2-transformed view is also available for advanced PFAS class differentiation. Additionally, 17 neutral losses characteristic of PFAS structures were added to the internal neutral loss library, improving fragmentation-based PFAS confirmation.

Top-Level Formulas Table

Before version 3.5, molecular formula assignments from different sources within a workflow were spread across multiple annotation layers. The new top-level Formulas table consolidates detected or predicted formulas from all annotation sources into a single unified view, making it far easier to review and adjudicate formula assignments without drilling into multiple sub-tables.

Chromeleon CDS Export

CD 3.5 can now export both the standard Compounds table and the GC/EI Compounds table directly to the Thermo Scientific Chromeleon Chromatography Data System (CDS). This integration closes a significant workflow gap for laboratories that use Chromeleon as their primary data management system, allowing quantitative and qualitative results from Compound Discoverer to be archived and audited alongside raw chromatographic data within a single CDS environment — an important consideration for regulated GxP laboratories.

New Targeted Stable Isotope Labeling Workflow

Stable isotope labeling (SIL) experiments are used in metabolic flux analysis to trace how carbon, nitrogen, or other atoms flow through metabolic pathways over time. While CD has supported untargeted isotope labeling workflows for some time, version 3.5 introduces a new dedicated template for targeted SIL experiments, making setup faster and more reproducible for researchers conducting quantitative flux studies.

Internal Loss Search Improvements

The Search Neutral Losses node was extended to support internal loss detection — losses between two fragment ions rather than only between the precursor and a fragment. The Neutral Losses library was also updated, with the new option to specify whether the loss occurs from the precursor or internally between fragments, providing more granular structural annotation of MS/MS spectra.

Responsive User Interface Scaling

A user-facing quality-of-life improvement: the UI now dynamically scales font sizes in most charts and views based on the display resolution and DPI settings of the host computer. For researchers working on high-resolution 4K monitors — increasingly common in modern laboratory workstations — this resolves the long-standing issue of illegibly small text in results tables and spectral views.

SIRIUS Node Integration (December 2025)

Shortly after the 3.5 release, Thermo Fisher made available the SIRIUS node for Compound Discoverer. SIRIUS is an open-source structural annotation tool developed by the Böcker group at Friedrich Schiller University Jena and widely used in the metabolomics community. It uses fragmentation trees and machine learning-based tools (CANOPUS, ZODIAC, CSI:FingerID) to predict molecular formulas, chemical classes, and structural fingerprints directly from MS/MS spectra. The SIRIUS node is free for academic use (requiring account registration), while commercial users require a separate SIRIUS commercial license. This integration makes CD 3.5 one of the most comprehensive annotation environments available for untargeted metabolomics.

Annotation Confidence Scoring (2026)

The most recent major addition to the platform — released in April 2026 — is the Annotation Confidence Scoring system. This framework provides a structured, multi-level confidence assessment for each compound annotation, drawing on spectral match quality, database evidence, formula plausibility, and the number of independent annotation sources that agree. It aligns with community-standard reporting frameworks like the Metabolomics Standards Initiative (MSI) confidence levels, giving researchers and reviewers a transparent, systematic basis for evaluating identification reliability rather than relying on intuition or raw score thresholds alone.

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Integration with the Ardia Platform

One of the strategic directions Thermo Fisher has pursued for CD 3.5 is cloud connectivity via the Ardia Platform. Ardia is Thermo Fisher’s laboratory data and collaboration platform, and its integration with CD 3.5 unlocks several capabilities that are not available in standalone mode:

• Direct raw data access — Ardia-connected CD can read instrument raw files directly from centralized storage rather than requiring local file copies.
• Result file upload and sharing — Completed analysis results can be uploaded to Ardia for team-wide access, enabling collaborative review workflows in multi-user laboratory environments.
• Remote accessibility — Researchers do not need to be physically present at the data processing workstation to access results or trigger reprocessing jobs.
• Data management and audit trails — Ardia’s platform layer provides metadata management, versioning, and access control that supports institutional data governance requirements.

For single-investigator academic labs, the standalone Compound Discoverer installation remains fully functional without Ardia. The cloud platform integration is primarily relevant for larger research groups and industrial or CRO environments where data sharing, version control, and remote access are operational priorities.

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Statistical Analysis and Visualization Tools

Compound identification is only half the value proposition of Compound Discoverer. The other half is its built-in statistical and visualization layer, which allows researchers to extract biological or chemical meaning from their datasets without exporting to external tools like R or Python (though such exports are still supported for advanced users).

Key statistical capabilities include:

• Principal Component Analysis (PCA) — interactive score and loading plots with color-coded sample groups, enabling rapid assessment of clustering, outliers, and batch effects.
• Partial Least Squares Discriminant Analysis (PLS-DA) — supervised multivariate analysis for identifying features that best discriminate between defined sample classes.
• Variance analysis and Volcano plots — for identifying statistically significant differences between two sample groups, with user-defined fold-change and p-value thresholds.
• Heat maps — hierarchically clustered feature-by-sample intensity matrices that provide visual summaries of entire dataset structures.
• Pathway mapping — via the integrated Metabolika module (for built-in KEGG-based mapping) and direct BioCyc query, identified compounds can be plotted onto biochemical pathways with fold-change overlays, enabling rapid hypothesis generation about which metabolic processes are perturbed between experimental groups.
• Molecular networking — a network-based visualization that groups features by spectral similarity, revealing structural relationships between known and unknown compounds even when direct identification is not possible.

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Compound Discoverer 3.5 License Options

Compound Discoverer is commercial software that requires a valid license to use beyond an initial evaluation period. Thermo Fisher offers a 60-day evaluation license that is activated automatically at the time of installation — this gives new users substantial time to evaluate the software against their real datasets before committing to a purchase.

Once the evaluation period ends, a purchased license is required. There are several license types available:

• Single-seat license — the most common option for individual researchers or small labs. The license is node-locked to a single computer and must be activated online through the Thermo Fisher LSMS licensing portal using an activation code provided at the time of purchase.
• Multi-seat license — for organizations running CD on multiple workstations simultaneously. Multi-seat licenses are managed through the same portal but cover a defined number of concurrent activations.
• Upgrade license — for existing customers who own a license for an earlier version (such as CD 3.3 or 3.4) and wish to upgrade to 3.5. Upgrade pricing is typically lower than a new full license.
• Academic license — Thermo Fisher typically offers preferential academic pricing through authorized resellers and institutional agreements. Academic purchasers should contact their local Thermo Fisher representative or regional distributor to obtain a quote.

The license activation process requires an internet connection on the target machine, though offline activation is possible by completing the activation steps on a separate internet-connected computer and transferring the license file. License management — including transfers between computers after hardware upgrades — is handled through the Thermo LSMS Software Download and Licensing Portal. For licensing questions or if an activation code cannot be located, the support contact is ThermoMSLicensing@thermofisher.com.

It is worth noting that some add-on capabilities — most notably the SIRIUS integration — carry their own separate licensing requirements. As mentioned above, SIRIUS is free for academic users (requiring a SIRIUS account registration) but requires a separate commercial license for industrial or for-profit applications.

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How to Download Compound Discoverer 3.5

The official download channel for Compound Discoverer 3.5 is the Thermo Fisher LSMS (Life Science Mass Spectrometry) Software Download and Licensing Portal, accessible at thermo.flexnetoperations.com. This portal requires a registered account, which is tied to your software purchase order or provided in the software media kit that accompanies a new license purchase.

Steps to obtain and install the software:

1. Register or log in to the LSMS Software Download and Licensing Portal using the credentials provided by Thermo Fisher at the time of purchase.
2. Locate your product — search for Compound Discoverer 3.5 in the product list associated with your account. The installer executable will be available for download.
3. Download the installer to a local drive on your Windows workstation. The installation package is a large file; a stable internet connection is recommended to avoid corrupted downloads.
4. Run the installer with administrator privileges on a 64-bit Windows system. CD 3.5 requires Windows 10 64-bit or Windows 11 64-bit and a US-English locale system setting.
5. Activate the license using the activation code or license file provided with your purchase. Online activation connects directly to the Thermo licensing server; offline activation generates a fingerprint file that is submitted via the portal on a separate machine.

Users upgrading from a previous version of Compound Discoverer do not need to uninstall the old version first. CD 3.5 can be installed in parallel with CD 3.4 or earlier versions on the same machine, allowing side-by-side comparison and a gradual transition to the new version before retiring the old installation.

For download access issues — for example, if your account cannot be located in the portal — contact ThermoMSLicensing@thermofisher.com with your sales order number, software application name, end-user name, and end-user email address.

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System Requirements

CD 3.5 is a Windows-only application. The official minimum and recommended hardware specifications reflect the computational demands of processing large LC-MS datasets:

• Operating system: Windows 10 64-bit or Windows 11 64-bit (US-English locale required)
• Processor: Multi-core 64-bit processor; higher core counts improve parallel processing performance significantly
• RAM: 16 GB minimum; 32 GB or more strongly recommended for large metabolomics studies with many samples
• Storage: SSD storage recommended for study files and result files; raw Orbitrap data files are large, and fast local storage substantially reduces processing time
• Internet connection: Required for license activation and for online mzCloud database searching; offline operation is possible with local spectral libraries after initial activation

The software stores study files (.cdStudy) and result files (.cdResult) on the local hard drive for optimal performance. Network-attached storage can be used for archiving raw data but is not recommended as the primary working directory during active data processing.

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Compound Discoverer 3.5 vs. Previous Versions

Researchers evaluating whether to upgrade from version 3.3 or 3.4 will find that the 3.5 release is a worthwhile step forward, even if the core workflow engine has not changed fundamentally. The most compelling reasons to upgrade are:

• The PFAS toolset is entirely new and will be essential for any lab that conducts PFAS screening or is preparing for regulatory compliance work.
• The improved FISh algorithm provides meaningfully better negative-mode annotations — something that affected a broad range of workflows.
• The SIRIUS node integration adds state-of-the-art ML-based annotation that was previously only accessible by exporting data to a separate tool.
• The Chromeleon export bridge is important for labs in regulated environments that manage data in Chromeleon CDS.
• The Annotation Confidence Scoring system (2026) is the first step toward fully standardized, transparent reporting of identification confidence — increasingly expected in peer-reviewed publications.

For labs still on version 3.3 or earlier, the upgrade also brings all the improvements from 3.4, including the LipidSearch node, mzCloud 2.0 access, molecular networking improvements, and QC tools for small molecule workflows.

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Frequently Asked Questions (FAQ)

Q1: Is Compound Discoverer 3.5 free to use?

Compound Discoverer 3.5 is not free software. It is a commercial product that requires a purchased license. However, Thermo Fisher provides a 60-day free evaluation period that begins automatically upon installation, during which the full software functionality is available. After the evaluation period, a valid activated license is required to continue using the software. There is no permanently free version, though academic institutions typically qualify for discounted pricing through Thermo Fisher’s education and research programs.

Q2: Where can I download Compound Discoverer 3.5?

The official download source is the Thermo Fisher LSMS Software Download and Licensing Portal (thermo.flexnetoperations.com). You must have a registered account linked to a valid purchase or evaluation registration to access the download. Downloading the software from unofficial third-party sources is not recommended, as such packages may be outdated, modified, or missing critical components required for proper installation and license activation.

Q3: What mass spectrometers are compatible with Compound Discoverer 3.5?

CD 3.5 is designed primarily for data from Thermo Scientific Orbitrap-based mass spectrometers, including the Q Exactive series (Q Exactive, Q Exactive Plus, Q Exactive HF, Q Exactive HF-X), the Orbitrap Exploris series (Exploris 120, 240, 480), the Orbitrap Eclipse, Orbitrap Fusion Lumos, and Orbitrap Astral. GC/EI data from the Orbitrap Exploris GC is supported through dedicated GC workflow nodes. The software processes Thermo Scientific .raw format data files natively; data from other vendors’ instruments requires conversion to mzML or similar open formats, which may limit functionality compared to native .raw processing.

Q4: Can Compound Discoverer 3.5 be installed on a computer without an internet connection?

Yes, with some limitations. The software can be installed on an air-gapped machine, but offline license activation is required — this involves generating a machine fingerprint on the target computer, submitting it via the licensing portal on a different internet-connected machine, and transferring the resulting license file back to the target machine. Once activated, the software runs fully offline. Online mzCloud database searching will not be available without internet access, but local spectral libraries (mzVault) and offline mass lists can be used as substitutes.

Q5: Is a separate license needed for the SIRIUS integration in CD 3.5?

Yes. The SIRIUS node for Compound Discoverer uses the SIRIUS software engine, which has its own licensing terms independent of the Compound Discoverer license. For academic researchers, SIRIUS is free of charge but requires registration of a SIRIUS account. For commercial or non-academic users, a SIRIUS commercial license must be purchased separately from the SIRIUS development team. This is handled independently of the Compound Discoverer purchase process with Thermo Fisher.

Q6: Can I transfer my Compound Discoverer license to a new computer?

Yes. License transfers are managed through the Thermo LSMS Software Download and Licensing Portal. The process typically involves deactivating the license on the old machine (which releases the activation slot) and then reactivating it on the new machine. If you are unable to deactivate the old installation (for example, after a hardware failure), you should contact ThermoMSLicensing@thermofisher.com with your order details, and they can manually release the license for reactivation.

Q7: Does Compound Discoverer 3.5 support GC-MS data, or is it only for LC-MS?

CD 3.5 supports both LC-MS and GC/EI-MS data. Dedicated GC/EI workflow nodes and templates are included for untargeted GC-Orbitrap data analysis. The GC/EI Compounds table can now also be exported to Chromeleon CDS as of version 3.5. That said, the software’s deepest feature set and the broadest library coverage are oriented toward LC-MS/MS data, which remains the primary use case for most users.

Q8: What happened to the LipidSearch standalone application in CD 3.5?

As of CD 3.4, the LipidSearch functionality was integrated directly as a node within Compound Discoverer via the LipidSearch (MKI) node. This means you do not need to install the LipidSearch standalone software separately to perform lipid identification in CD 3.5. The integrated node provides simplified, streamlined lipidomics workflow setup within the standard CD workflow editor, making it accessible to users who may not have specialized lipidomics expertise.

Q9: What is the Ardia Platform and is it required to use CD 3.5?

The Ardia Platform is Thermo Fisher’s cloud-based laboratory data and collaboration system. In CD 3.5, Ardia connectivity enables features such as direct raw data access from centralized storage, result file upload and sharing, and remote accessibility. However, Ardia connectivity is entirely optional. Compound Discoverer 3.5 functions fully as a standalone desktop application without any connection to the Ardia Platform. Labs that do not require cloud data management or remote collaboration will not notice any feature limitations from operating in standalone mode.

Q10: What are the new PFAS features in Compound Discoverer 3.5?

Version 3.5 introduced a comprehensive PFAS analysis toolkit. This includes the PFAS Scoring node for systematic prioritization of PFAS candidates, the PFAS Plot for visualizing fluorinated compound chemical space via normalized mass defect versus normalized mass (with optional CF2-transformed view), the addition of 17 PFAS-characteristic neutral losses to the internal library, and extended Internal Loss Search functionality for detecting losses between two fragments rather than only from the precursor. Together, these tools make CD 3.5 the most capable version of the software for non-targeted PFAS screening workflows.

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Conclusion

Thermo Scientific Compound Discoverer 3.5 is the most capable version of this platform to date. It consolidates years of user feedback and emerging scientific needs — particularly around PFAS analysis, negative-mode fragmentation scoring, GxP-relevant data export, and state-of-the-art structural annotation via SIRIUS — into a single, cohesive upgrade that makes a compelling case for both new adopters and users considering a license upgrade from earlier versions.

The node-based workflow architecture remains the software’s strongest differentiator: it provides the flexibility to address radically different analytical questions from a shared interface and a common processing engine, without sacrificing depth in any individual application area. Combined with the 2026 additions of SIRIUS integration, Annotation Confidence Scoring, and ongoing Ardia Platform development, CD 3.5 is positioned as the foundation of Thermo Fisher’s metabolomics and small-molecule software ecosystem for the foreseeable future.

For researchers ready to evaluate the software, a 60-day evaluation license is available upon installation from the LSMS portal. For those managing the download and activation of a purchased license, the Thermo Fisher licensing support team is reachable at ThermoMSLicensing@thermofisher.com with purchase order or sales order details. Whether your work focuses on metabolomics, PFAS, pharmaceutical impurity identification, food safety, or any of the many other disciplines served by high-resolution mass spectrometry, Compound Discoverer 3.5 represents a mature, actively developed, and scientifically rigorous tool worthy of serious evaluation.

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