Extract Domains From CSV, HTML, XML and JSON Files

Upload common text-based export formats, extract domains locally and preserve source files and line numbers in a structured report.

FlashDomains Editorial·August 21, 2026·8 min read

URLs rarely arrive as a plain text list. SEO platforms export CSV, page templates contain HTML, sitemaps use XML and APIs return JSON. Converting every format by hand before extracting domains creates unnecessary work and can remove useful context.

FlashDomains reads supported text-based files directly in the browser. You can combine several files, add pasted text and produce one domain report without uploading the source to a server.

Supported file workflows

Format	Typical content	What the scanner reads
CSV	Crawl, backlink or contact export	Domain-shaped values across cells and rows
HTML / HTM	Saved markup or template	URLs inside attributes and visible text
XML	Sitemap or feed export	URLs and hostnames in text nodes
JSON	API response or structured log	Domain-shaped strings inside the document
TXT / LOG	Lists and server output	Mixed URL, email and hostname patterns

How to process several files together

Keep a backup. Treat extraction as a derived report, not a replacement for the originals.
Select or drop the files. The current limits are 20 MB per file and 50 MB combined.
Add optional pasted input. It becomes a separate named source in the same report.
Choose a preset. Backlink audit returns roots; migration and security presets preserve hostnames.
Inspect and export. Filter the table, review rejected lines and download TXT, CSV or JSON.

Repeatable process

Extract domains from structured text files

Keep file and line provenance while handling several common export formats together.

1
Preserve an untouched copy
Keep the original CSV, HTML, XML or JSON export before any cleanup or conversion.
2
Upload supported files
Add one or several text-based files within the browser limits.
3
Review matches by source
Use filenames and line numbers to distinguish content links, assets, metadata and API values.
4
Filter and export
Select the relevant result kinds, deduplicate at the right boundary and download the report.

Side-by-side

What domain-shaped values appear in each format?

Format affects where values are found and what context should be retained.

Decision	Common locations	Review concern
CSV	URL columns, notes and exported cells	Quoted fields and unrelated text columns
HTML	href, src, canonical and structured data	Assets versus navigational links
XML	Sitemap loc values, attributes and text nodes	Namespaces and non-URL identifiers
JSON	API fields, configuration and nested strings	Property names that resemble domains

Where it helps

File-based extraction workflows

Use the cleaned output as a focused input to the next analysis—not as a substitute for that analysis.

SEO exports

Normalize crawl, backlink and analytics files without spreadsheet formulas.

Saved webpages

Inventory linked, embedded and metadata hosts in downloaded HTML.

Sitemaps

Reduce XML URL inventories to the hosts represented in the files.

Configuration audits

Find API, CDN and service domains inside permitted JSON configuration exports.

Worked example

Combine values from different file formats

Input

CSV: source,https://publisher.com/a
HTML: <a href="https://docs.example.org">
JSON: {"api":"https://api.example.net/v2"}

Result

publisher.com
example.org
example.net

Source mapping identifies the file and line responsible for each match.

CSV considerations

The scanner looks throughout the text rather than requiring a particular column name. That is convenient for mixed exports, but it means URLs in notes, target columns and metadata can all be recognized. Use the source-line mapping to confirm which field produced a result. If column-perfect transformations are required, parse the CSV with a dedicated data pipeline.

HTML considerations

Saved HTML can contain page links, image sources, scripts, stylesheets, canonical URLs and structured data. A domain extractor reports domain-shaped values but does not execute the document or render JavaScript. Filter out asset hosts only after deciding whether they matter to your audit.

XML and sitemap considerations

An XML sitemap normally lists URLs intended for one site, but sitemap indexes and exported feeds can reference several hosts. Extraction summarizes the hostnames present; it does not validate XML syntax, sitemap eligibility, response codes or indexability.

JSON considerations

JSON may contain escaped URLs, identifiers and nested metadata. The text scanner finds recognizable domain values without needing the property path. Use the JSON export when downstream code needs the structured result and source records.

Privacy and performance

File contents are read through browser file APIs and processed in a background worker. Nothing is sent to a FlashDomains account. Large files still consume memory on your device, so split unusually large datasets or build a streaming server-side pipeline for recurring enterprise jobs.

For mixed prose and copied reports, read extracting domain names from text. For counted output, see removing duplicate domains.

Frequently asked questions

Does the tool modify my files?

No. It reads them and creates a separate result for download.

Can I upload XLSX or PDF?

Not currently. Export a relevant worksheet as CSV or copy text from a PDF first.

Can files and pasted text be combined?

Yes. Each remains identifiable as a separate source in the structured report.