FTIR spectroscopy · in your browser

Analyse FTIR spectra.
Fast, visual, private.

Import, preprocess, compare and deconvolve infrared spectra without installing anything. Your files are processed locally and never leave your device.

Import a spectrum Sample spectrum

CSV / TSV / TXT
XLSX / ODS
DPT
SPC
OPUS .0
OMNIC .spa / .spg
PerkinElmer .sp
Spotlight .lsc / .fsm
JCAMP-DX

Import

Load your data

One spectrum, or several to compare. Drag files onto the area below.

Choose a file or drag it here CSV/TXT · Excel · SPC · OPUS · OMNIC .spa/.spg · PerkinElmer .sp/.lsc/.fsm · JCAMP-DX

Choose files or drag them here Select several files at once No files selected

Visualize

Spectrum

Preprocessing

Baseline Correction ⓘ

Smoothing ⓘ

Normalization ⓘ

Offset Correction ⓘ

Apply automatic offset

Click-to-set offset

Click a point on a spectrum to set its offset (Absorbance → 0, Transmittance → 100%).

Export processed data

Spectra exactly as displayed, including all active preprocessing.

Library

Reference spectra

Overlay standard compounds on your spectrum, or load your own JSON / JCAMP-DX references.

0 compounds

Select a compound to view details

Deconvolution

Peak fitting

Decompose overlapping bands into pseudo-Voigt peaks with an ADAM optimizer. Fitting is done on the imported data, in absorbance.

ⓘ

1Choose the spectrum and region
2Click each peak on the preview — or let the derivatives suggest them
3Run the fit

Spectrum ⓘ

Region (cm⁻¹) ⓘ

–

Baseline ⓘ

Peaks ⓘ

No peaks yet — show the region and click on each peak.

Peak definitions ⓘ

On ⓘ		Name ⓘ	Freq (cm⁻¹) ⓘ	± Freq ⓘ	FWHM (cm⁻¹) ⓘ	± FWHM ⓘ	L % ⓘ	L min ⓘ	L max ⓘ	ε (mol. ext.) ⓘ

ADAM optimizer ⓘ

Multi-start runs ⓘ

Max iterations ⓘ

Learning rate ⓘ

R² target ⓘ

Simple mode uses these optimizer settings too.

Fit result

R² ⓘ --

R² Abs ⓘ --

Area error ⓘ --

Max discrepancy ⓘ --

Convergence ⓘ --

Species quantification ⓘ

	Species	Freq (cm⁻¹) ⓘ	FWHM (cm⁻¹) ⓘ	Intensity ⓘ	Area (Simpson) ⓘ	% Area ⓘ	L % ⓘ	Conc. (mmol/cm³) ⓘ

Derivative analysis ⓘ

Composition

Reference contribution

Fits your spectrum, in absorbance, as a sum of reference spectra (Beer-Lambert) and reports how much of its band area each one explains. A content in % is only given for references you measured yourself as pure substances under the same conditions.

ⓘ

Sample

Data ⓘ

Region (cm⁻¹) ⓘ

–

Background ⓘ

Exclude CO₂ (2280–2400 cm⁻¹)

References ⓘ

No references yet.

R² ⓘ --

Unexplained area ⓘ --

Points fitted ⓘ --

	Reference	Scale k ⓘ	Band-area share ⓘ	Content ⓘ

Indices

Spectral indices

Define an index as a formula over spectral regions (e.g. CI = C / R, with C the area 1850–1650 cm⁻¹ and R the area 1500–1420 cm⁻¹), choose how each region is measured, and compute it for every loaded spectrum. Definitions can be saved in this browser and exported as JSON.

ⓘ

Index definition

Name

Formula ⓘ

Notes

Regions ⓘ

	Name	From (cm⁻¹)	To (cm⁻¹)	Measure	Baseline	Anchor windows (cm⁻¹)	Shape

Processing

Data ⓘ

Smoothing

Offset ⓘ

Integration ⓘ

arPLS smoothness ⓘ

Sensitivity ± cm⁻¹ ⓘ

Warn above (%)

Ignore signal below the baseline

Preview spectrum

Index —

Drag a dotted anchor band to move it, or grab just inside one of its edges to resize it. The table updates as you drop it.