Cleaned Sequence
Sanitized input after removing FASTA headers, spacing, digits, and unsupported symbols.
Input
Paste DNA, RNA, or FASTA text
Cleaning summary
Paste a sequence to review sanitization details and sequence type detection.
Outputs
Transformed sequences
Aligned Complement, 3'→5'
Base-by-base complement aligned to a 5'→3' input DNA-style strand.
Reverse Sequence
The cleaned input in reverse order without complementing bases.
Reverse Complement, 5'→3'
Reverse the sequence, then complement each base in a single pass.
RNA from Coding DNA, 5'→3'
Treat the cleaned input as coding DNA and convert thymine to uracil.
RNA from Template DNA, 5'→3'
RNA complement produced from a template or antisense DNA strand.
DNA from RNA
Convert uracil back to thymine for quick RNA-to-DNA normalization.
Metrics
Sequence composition
Ambiguous bases are excluded from GC% and AT% calculations.
Guide
How SeqFlip Works
Complement vs reverse complement
The aligned complement is shown base-for-base against the input, so its direction is 3'→5'. The reverse complement flips the strand and complements it, yielding a 5'→3' sequence.
Coding vs template transcription
RNA from coding DNA keeps the same base order as the coding strand except T becomes U. RNA from template DNA is the RNA complement generated from the antisense strand.
GC denominator
GC% and AT% use only canonical bases A, T, U, C, and G. Ambiguous IUPAC symbols are excluded so the percentages stay biologically interpretable.
Ambiguous IUPAC bases
Symbols such as N, R, and Y are preserved during cleaning, counted separately, and excluded from GC% so you can inspect uncertainty without overstating precision.
Local-first privacy
SeqFlip runs in your browser only. It does not require an account, does not store pasted sequences, and now uses Google Analytics for site traffic measurement.
FAQ
Common Questions
What is a reverse complement?
A reverse complement is the opposite DNA strand rewritten in the 5'→3' direction after reversing the input and complementing each base.
Is my sequence uploaded?
No. SeqFlip processes sequence text locally in your browser and does not intentionally upload or store pasted sequences.
Does SeqFlip support FASTA?
Yes. FASTA header lines that begin with > are removed before the remaining sequence text is cleaned.
How is GC% calculated?
GC% uses only canonical bases. The denominator is A, T, U, C, and G, while ambiguous bases are excluded.
What are ambiguous nucleotide bases?
Ambiguous nucleotide bases are IUPAC symbols such as N, R, or Y that represent multiple possible nucleotides and may affect interpretation.
Trust
Privacy, Terms, and Disclaimer
Privacy-first operation
SeqFlip is a local browser utility. It does not intentionally upload or store your sequence data, and clipboard use happens only when you press Copy.
Use and validation
SeqFlip is provided for educational, research, and informational use. You are responsible for validating results before laboratory, clinical, regulatory, or production use.
Important disclaimer
SeqFlip does not provide medical advice and is not a substitute for validated bioinformatics pipelines, laboratory workflows, or expert review.
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