Analyze 1D and 2D spectra from Bruker data, exported files or pictures, predict ¹H, ¹³C and ¹⁵N shifts from a structure, and compare them with nmrshiftdb2.
Loading…
Drag across the spectrum to zoom; double-click for the full view. Switch to Drag to integrate to draw your own integration region. Raise Height to see small signals.
Stacked spectra: experimental vs calculated
Report line
Report
δ (ppm)
Mult.
J (Hz)
Protons
Assignment
Lines
Interpretation & assignment
δ (ppm)
Signal
What it tells you
Assignment
AI-assisted interpretationassigns each signal, explains it and flags what does not fit
or another assistant:
Export:
Structure check
Enter the structure in Predict from structure and this panel checks it against the spectrum.
Structure
Need a structure to try?
Draw in the editor or paste SMILES. Predictions update as you draw.
Predicted spectrum
Prediction method: click one to draw its spectrum above (the table shows all of them)
Carbon numbers used in the table
Predicted ¹³C shifts use nmrshiftdb2 where the atom environment has a close match, otherwise additivity rules (Grant–Paul and substituent tables); ¹H uses Pretsch and Beauchamp increments with first-order couplings. Typical error is ±0.2 ppm for ¹H and ±3 ppm for ¹³C, larger for crowded or strained structures. The dashed trace in the Analyze tab shows the same prediction over your spectrum.
Find the structure
Start from what you know about the unknown. Every candidate is simulated and ranked against the spectra open in Analyze.
Elements besides C and H:
No formula? The spectra open in Analyze give the H count (integrals), the C count (¹³C lines), and the degree of unsaturation (aromatic and C=O signals). Every formula that fits is searched and all candidates are simulated and ranked, with probabilities. Adding a molecular ion or elemental analysis below narrows it down.
Elements besides C and H:
Logic structure generator
spectra → building blocks → every way to join them → rules → ranking
Reads the spectra like a chemist: aromatic H → ring pattern, q + t → ethyl, sept + d → isopropyl, 3H singlet at 3.3–4.1 → OCH₃, aldehyde and exchangeable H, the integral of every other signal → CH₃ / CH₂ / CH. The atoms left over are added, every connectivity is built, chemically impossible ones are dropped, the ¹³C signal count must match, and the rest are simulated and ranked with the candidates above.
PRISM round trip · peak list ⇄ structure
idea: Hoque & Glorius, Angew. Chem. Int. Ed. 2026
PRISM is a transformer that turns ¹H/¹³C δ-lists plus a formula into a ranked beam of SMILES, and structures back into δ-lists. Here: your spectra are formatted for PRISM, its beam is pasted back, and every candidate is sent back to spectra with this app's predictor and scored against your data. A candidate that survives both directions is the one to trust.
Paste PRISM's beamone candidate per line, best first; a log-probability on the line is kept
Structure → spectrum (the way back)
Results appear here: beam rank, formula check, predicted δ-lists and agreement with your spectra.
Probability of each candidate
Elemental analysis is taken from the Elemental analysis fields above when filled in; ¹H and ¹³C from the spectra open in Analyze.
Enter a formula, a mass or an elemental analysis to see candidate structures.
This is the same structure as in Predict: whatever you draw here is predicted there too, and the reverse.
Properties calculator
Mass spectrum
Isotope pattern
Fragmentation
3D model and measurements
Press Build 3D model.
Functional groups, IR and NMR ranges
Reaction table
Row 1 is the limiting reagent. Change any value and the rest follow: equivalents, mmol, mass, or volume (with density). Type a formula (e.g. C7H6O) or SMILES as the name to fill the molar mass.
Compound
M (g/mol)
equiv
mmol
mg
ρ (g/mL)
mL
Product and yield
Solution
My structure library
The library is kept in this browser only. Export it to back it up or move it to another computer.
Export the structure
SVG and MOL open in ChemDraw, ChemSketch, Word and most drawing programs.
Drag a box to zoom; double-click for the full view. Dots are picked cross peaks (teal positive, magenta negative). Amber circles (HSQC) and squares (HMBC) are the correlations expected from the structure in the Predict tab. The traces along the edges are projections of the 2D data, or for peak lists and pictures, your ¹H spectrum from Analyze or the predicted one.
Cross peaks
Assignments pair each cross peak with the nearest predicted correlation (¹H within about 0.25 ppm, ¹³C within 4 ppm, ¹⁵N within 15 ppm). They are suggestions to check against the 1D data, not proof of structure. In HMBC, aromatic ³J correlations are usually stronger than ²J.
Start in four steps
Open a spectrum. Use Open spectrum file for CSV/TXT, JCAMP-DX, MestReNova peak lists, PDFs and pictures, or Open Bruker folder for TopSpin data. A ZIP of a Bruker folder works too.
Check the Analyze tab. Peaks, multiplets, J and integrals are picked automatically. Drag to zoom; switch to Drag to integrate to set regions yourself.
Enter the structure. Draw it or paste SMILES in Predict from structure. Empirical shifts, the nmrshiftdb2 lookup and the overlay on your spectrum update by themselves.
Assign 2D data and write the report. HSQC, HMBC and COSY peaks are matched to atoms in the 2D tab; the Report tab builds the figure, tables and methods text.
Tutorials
Guided tours open the right tab, highlight each control and can do every step for you. Lessons explain the chemistry behind it.
Structure examples
Click Open in Predict to load a structure: predictions, method tabs, Chem tools and Find structure use it at once.
Spectrum examples
1D · peak list
1,10-Phenanthroline ¹H
MestReNova peak table in DMSO-d₆ with solvent, impurity and ¹³C-satellite flags.
1D · peak list
1,10-Phenanthroline ¹³C
Six aromatic carbons and the DMSO-d₆ septet; compare with nmrshiftdb2 in Predict.
1D · spectrum
Ethylbenzene ¹H
Simulated 400 MHz spectrum with a quartet, triplet and aromatic multiplet.
2D · HSQC
Phenanthroline HSQC
Edited ¹H–¹³C map built from the 1D shifts; four CH correlations.
2D · HMBC
Phenanthroline HMBC
Eleven long-range ²J/³J correlations, including the quaternary carbons.
2D · ¹⁵N
¹H–¹⁵N HMBC
Peak list for the pyridine-type nitrogen of phenanthroline.
Files it reads
Source
What to open
Bruker TopSpin
The experiment folder (acqus + fid or ser, optional pdata/1), a ZIP of it, or all its files selected together. Raw data are processed here; processed 1r/2rr are used when present.
MestReNova / TopSpin peak list
Tab-separated table with a ppm column; paste it or open the .txt.
Spectrum as numbers
CSV/TXT with ppm and intensity columns, or JCAMP-DX (.jdx, .dx).
2D matrix
CSV/TXT matrix with axes, TopSpin totxt export, or a list of δH, δC/δN pairs.
Pictures
PNG, JPG, TIFF, SVG, WebP, or a page of a PDF. Set the ppm at the frame edges.
Tips
Unknown compound: open its ¹H (and ¹³C) spectrum, then type the formula, the mass or the elemental analysis in Find structure to get ranked candidate structures.
Bruker phase looks wrong: use Flip 180° or type the phase in Bruker processing.
Peak list without J: export shifts with 3–4 decimals.
HSQC or HMBC looks upside down: tick Mirror F1 axis in the 2D tab.
Small cross peaks missing: lower the contour threshold.
Integrals off: set Total protons or type the H count of one signal.
Different solvent: pick it under Experiment; solvent peaks and the database lookup follow.
About
NMR Peak Reader
Created by Prof. Dr. Murad A. AlDamen
Department of Chemistry, School of Science The University of Jordan, Amman, Jordan
Data and software
¹³C database: nmrshiftdb2 (S. Kuhn, C. Steinbeck et al.), HOSE-code tables from vamos-hose 1.2.1, AGPL-3.0, loaded from jsDelivr.
Structures, 2D/3D coordinates and force field: OpenChemLib (BSD-3).