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Molbiotools is a collection of free online apps:

DNA Sequence Tools
Text and Data Tools
Lab Calculators
Math Calculators

DNA Sequence Tools

Restriction Analyzer

Carry out in silico restriction analysis online. Quickly find absent and unique sites. Tabular and graphical output. Analyze restriction fragments. Simulate a gel electrophoresis.

Silent Mutator

In silico silent mutagenesis online tool. Introduce new restriction sites without changing the encoded amino acid sequence. Supports all commercially available restriction enzymes. Supports all genetic codes. Unlimited sequence length.

Random Sequence Generator

Generate random DNA, RNA or protein sequences. Based on the Mersenne Twister algorithm. No unwanted repeats are generated even in very long sequences. Can be used for calculations of DNA, RNA and protein molecular weights and for string reverse and complement transformations (also with user-provided sequences).

Text and Data Tools

Target Text Extractor

Find and extract or remove target text patterns. Extract text between words. Extract words that begin with specific characters. Extract gene symbols from complex annotations. Online regular expression searching and match-extracting tool.

Multiple List Comparator

Compare data lists to find shared items. Find intersections among large data sets. Tabular data import (optional). Venn diagram drawing tool (png and svg export). Compare up to 100 lists.

List Operations

Perform set operations on data lists (union, intersection, subtraction). Remove duplicate items. Sort, reverse, or shuffle a list.

Table Operations

Remove rows or columns by number, order patterns, or specific content such as numeric value ranges or character patterns. Modify cell contents by removing, replacing, prefixing or appending characters. Rearrange tables by moving columns under each other. Easy transfer of data from and back into a spreadsheet software.

Two-table Operations

Extract or remove table rows with a selection list. Extract table rows by reference columns match. Align two tables.

Random Gene Set Generator

Generate random gene lists of defined length. Challenge GSEA results with random gene sets to estimate true significance of enrichments found with real data.

Lab Calculators

DNA Calculator

Calculate basic chemical properties of a DNA or RNA molecule. Calculate concentration from 260 nm absorbance. Calculate molarity, mass or volume. Calculate base-pair molarity of dsDNA solutions.

Chemical Calculator

Calculate molarity, mass or volume. Calculate molarity from percentual concentration. Calculate dilution of stock solutions.

Buffer Calculator

With this tool you can estimate the pH value of a buffer solution with Henderson-Hasselbalch equation. Also, a list of pKa values of common buffers is provided.


Experiment protocols may contain both relative centrifugation force (RCF) and revolutions per minute (RPM) values in centrifugation parameter specifications. This tool allows you to convert between RCF and RPM.

Math Calculators


How many different selections of items from a collection can you get? How many times a set of items can be rearranged? Use this tool to calculate numbers of combinations and permutations.


Calculate probabilities of random events following one the distributions: