SEOptimum
English · Română · Français · Italiano · Español · Português · Deutsch · Magyar
Version: 2.2.10 · Last updated: 2026-11-13
Status: stable · Offline: complete; "Try fetch" needs internet and the target site's CORS consent
Interface languages: Română, English, Français, Italiano, Español, Português (PT), Deutsch, Magyar
An SEO workshop in a single HTML file: twenty-one tools that run in the browser.
Live app: https://chiuta.github.io/SEOptimum/
What it is
SEOptimum ("offline SEO workbench") brings together tools for on-page auditing, structured data, technical files, content, off-page and local SEO. The analysis is done in the browser tab, on the text or HTML you paste; the app has no accounts and no analytics. The interface is available in English and Romanian (the "EN" / "RO" buttons).
Features
The menu contains 21 tools, grouped as follows:
- Content & on-page: on-page analyzer (title, headings, images, links, meta, structured data, target keyword), SERP and social preview (Google desktop/mobile, Facebook/LinkedIn, X/Twitter), meta tag generator, Schema / JSON-LD (building and validation, rich result preview), keyword research (density and n-grams, clustering, intent and long-tail, cannibalization), readability (six formulas, featured snippet check), duplicate content checker, competitor comparison.
- Technical: technical files (robots.txt, sitemap.xml, redirects, hreflang, llms.txt and other files generated in the app), log analyzer, internal structure and click depth, site audit, slug optimizer, Core Web Vitals check (rates values you type in; measures nothing).
- Off-page & local: anchor text analyzer, NAP consistency checker.
- Utilities: UTM builder, WCAG 2.2 contrast checker, GTIN / barcode validator (UPC-A, EAN-8, EAN-13, GTIN-14).
- Reference: SEO checklist (Markdown export) and reference sheet.
- Quick structured-data check: in the on-page analyzer, every JSON-LD block found has the button "Check required fields in the Schema tool →", which sends it to the Validate tab and runs the validation.
- Keyboard shortcut:
Ctrl/Cmd+Enter in a text field presses the nearest main button (Analyze, Generate, Check, etc.).
- Action plan (2.0): below the on-page analysis, fixes are listed by estimated impact, then effort (rule-of-thumb estimates, not ranking guarantees). Save a baseline, change the page, analyze again: see what was fixed, what is new and how the metrics moved. Snapshots can be downloaded/loaded as
.json.
- On-page report export (
on-page-report.md) and printing.
User guide
- Open the page and choose the language with "EN" / "RO"; the theme can be changed from the header.
- From the left-hand menu choose a tool (for example
<on-page/>).
- In the on-page analyzer, paste the page's HTML source (in the browser: Ctrl/Cmd+U, copy) into "Page HTML source", optionally fill in "Focus keyword" and press "Analyze".
- Optionally, fill in "Page URL" and press "Try fetch" to attempt a direct download; most sites block the request (CORS), in which case you use manual pasting.
- Use "Export report" to download the
.md report or "Print report".
- In the generators (meta, schema, UTM, etc.) fill in the fields and press "Copy".
- In the UTM builder, "Save to list" keeps the saved links in this browser.
- In the "SEO audit checklist" tick the items; the state is kept locally, and the export produces
seo-checklist.md.
Privacy and network
-
Local storage: localStorage, keys with the prefix seoFF. (language, theme, saved UTM list, checklist state).
-
Network: the app makes requests only on explicit user actions: the "Try fetch" button (fetch to the URL you enter, to any site) and the preview of an og:image image given by URL (the browser loads the image from that URL). The page's CSP allows these connections (connect-src *, img-src https: http:). Otherwise the analysis takes place locally; there is no CDN, external fonts or analytics.
-
The domains example.com, schema.org, etc. in the code appear as examples or vocabulary identifiers, not as loaded resources.
-
CSP: scripts are allowed only via a sha256 hash (no 'unsafe-inline' for scripts); the report print window no longer uses an inline script (printing is started from the main tab). Inline styles remain allowed.
Running locally / offline
Download index.html and open it in a browser; it works without internet. Only "Try fetch" and the preview of remote images need a connection.
License
MIT for the app's code and structure — see the LICENSE file. Any third-party libraries included in the file keep their own licenses.
Audit
Audit: 2026-10-10 — verified with Playwright and axe-core (WCAG 2.1 AA); colour contrast and horizontal overflow on narrow screens were fixed. The frame-ancestors directive was removed from the CSP meta (browsers ignore it in <meta>; it works only as an HTTP header, which GitHub Pages does not allow). connect-src * and img-src https: http: remain intentionally broad, because "Try fetch" and the og:image preview load arbitrary URLs entered by the user; they cannot be restricted without breaking the feature.
Author
Alexio — Alexandru-Ionuț Chiuță, contact: [email protected]
Summary
SEOptimum is a single-file SEO workbench with 21 tools (on-page analyzer, SERP/social preview, meta and JSON-LD generators, keyword research, readability, robots/sitemap/hreflang/llms.txt, log analyzer, site audit, UTM builder, WCAG contrast, GTIN validator, checklist). English/Romanian UI. Analysis runs locally; the network is used only for the optional "Try fetch" button and remote og:image previews. Preferences are stored in localStorage (seoFF. keys).
This is the beginning of the README. Read the rest at the original. Read the full README ↗
