Sequence Comparison Tool

Identify mutations between reference and query sequences

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Reference Sequence

Upload FASTA/TXT

Drag & drop your file here or click to browse

NCBI Accession ID

No sequence loaded

Query Sequence

Upload FASTA/TXT

Drag & drop your file here or click to browse

NCBI Accession ID

No sequence loaded

How to Cite This Tool

APA Format

Priyam, J. (2025). Jyotsna's NCBI Tools - Sequence Comparison Tool. DOI: https://doi.org/10.5281/zenodo.15069907

MLA Format

Priyam, J. "Jyotsna's NCBI Tools - Sequence Comparison Tool." 2025, DOI: https://doi.org/10.5281/zenodo.15069907. Accessed April 23, 2026.

BibTeX Format

@software{10_5281_zenodo_15069907, author = {Priyam, J.}, title = {Jyotsna's NCBI Tools - Sequence Comparison Tool}, year = {2025}, version = {1.0.0}, doi = {https://doi.org/10.5281/zenodo.15069907}, url = {https://ncbi.jyotsnapriyam.com/sequence-comparison}, note = {Accessed: April 23, 2026} }

How to use the Sequence Comparison Tool

Compare a reference and query sequence to list substitutions, insertions, and deletions after pairwise alignment. Use the same molecule type on both sides (DNA/RNA with DNA/RNA, or protein with protein) and overlapping regions for interpretable results.

  1. Reference sequence. In Reference Sequence, upload FASTA or TXT (drag-and-drop or browse) or enter an NCBI accession (e.g. NC_045512.2) and Fetch. Wait until the status line confirms loading.
    • FASTA: optional > header; sequence is read from the body.
  2. Query sequence. In Query Sequence, upload or Fetch the same way. Both must load before comparison runs.
  3. Compare. Click Compare Sequences when enabled. Long or very large fetches may be slow or warn; if fetch fails, obtain a subsequence from NCBI and upload it.
  4. Results. Comparison Results include summary statistics (mutation count, length, mutation rate), metadata, a mutation distribution plot, an alignment with highlights, and a mutation table (position, reference, query, type).
  5. Filters (optional). Checkboxes: All Mutations, or only Substitutions, Insertions, or Deletions. The plot and table update accordingly.
  6. Export. Use Download PDF report (server), Simple PDF / print (browser), or Export as Image as needed. Citation formats are provided at How to Cite This Tool in this tool.
  7. Reset. Clear All removes inputs and results for a new run.

Scope: Output reflects a local pairwise alignment (a strong matching segment), not necessarily whole-chromosome end-to-end alignment. For database-wide similarity, use BLAST Sequence Search. For research and teaching, not clinical use.

Frequently Asked Questions

What types of sequences can I compare with this tool?

This tool can compare DNA and RNA sequences in various formats, including FASTA and plain text. You can directly upload sequence files or fetch sequences from NCBI using their accession IDs.

How does the sequence comparison algorithm work?

The tool runs a local pairwise alignment: it finds a strong matching segment between your reference and query, not necessarily full end-to-end alignment of both entire sequences. Differences in that aligned segment are reported as substitutions, insertions, or deletions. Summary statistics and charts (for example mutation distribution) refer to that aligned region, as noted on the results page.

Can I filter the mutation results?

Yes. Use the checkboxes to show all mutations or only substitutions, insertions, or deletions. There are no separate controls to filter by base-pair position range; trim your sequences before upload or fetch if you need a specific window.

What information is included in the PDF report?

The PDF report includes comprehensive analysis details: summary statistics, sequence metadata, a visualization of mutation distribution, a complete table of all mutations with their positions and types, and citation information for academic use.

How can I cite this tool in my research?

You can cite this tool using standard academic formats (APA, MLA, Chicago) with the DOI: https://doi.org/10.5281/zenodo.15069907. Citation formats are provided at the bottom of the results page and included in the generated PDF reports.

What is the maximum sequence length this tool can handle?

Many comparisons complete comfortably in the kilobase to low megabase range. NCBI fetch limits depend on server configuration (often on the order of a few million base pairs). Longer sequences may run slowly, time out, or trigger warnings in the UI; multi-megabase or chromosome-scale jobs are better suited to specialized desktop tools.