Before you buy, get a link or publish, check the domain’s history first.

Kosto shows a domain's authority score from its link index and digs through the web archive for gambling, pharma, adult content and hack traces. It draws what it finds year by year.

See the score without signing up. Signing up for the full report is free, no card needed.See a sample report
Dig cross-section · example-blog.comsample data
68/100 risk

Risky. 214 addresses were examined, 96 were flagged as gambling pages. First trace in 2022.

Something smells off here. The topic changed after 2022.
Kosto the mole in a miner's helmet, frowning at something

Familiar scenes

Most of these mistakes could have been checked before paying.

And checking meant digging through an archive by hand.

  1. You paid for an expired domain. Two weeks later you look at the archive: gambling pages.
  2. You got a post on a blog, and three months later the link is gone from the page. Nobody told you.
  3. You told a client "let's get a link from this site". The site was hacked last year and still serves Japanese pharma pages.
  4. You log into five tools for a report. Each gives a different score, and none tells you why.

Six sections

First you look at what happened, then you decide.

1 · Spam history audit

See what happened in a domain's history, year by year.

Kosto looks at the web archive, the crawl index and the live site. It looks for traces in categories such as gambling, adult content, pharma, counterfeit goods, loan and crypto scams, and foreign-language spam after a hack. The result is a timeline split by year: how many pages were seen in which year, how many were flagged, and which sample addresses.

The verdict has four levels: looks clean, suspicious, risky, strong spam traces. Every score shows which finding it came from. There are no unexplained scores.

Spam audit · example-blog.com sample domain
68/100

First trace in 2022. The flagged page share has been rising over the last three years.

Risky
Pages seen (sample)Flagged share
Gambling62%
Pharma21%
Loans9%
Foreign language4%
214 addresses were examined. Yearly counts are a sample, not the real page count of the site.
Traffic and keywords · example-blog.com sample data
Monthly organic traffic: 12,400 estimatedRanking keywords: 1.860In the top 10: 214
KeywordMonthly searchesRankDifficulty
sample keyword one4.400338
sample keyword two1.900746
sample keyword three8801229
sample keyword four3901821
Sample view. Traffic figures are estimates, not real visit counts. A cached result is free; a new fetch is deducted from your data quota.

2 · Search data

Traffic, keywords and rankings: paid, but measured.

The panel has a "Search data" group: estimated organic traffic and keywords, keyword research, keyword gap between two sites, page-level backlinks and rank tracking for specific keywords.

This data is paid and measured by quota. Every fetch button shows its cost, nothing is fetched unless you ask, and a cached result is free. Traffic figures are labeled "estimated" everywhere.

3 · Authority score

One number, an open calculation.

71Strong · sample data
Network position
Strength of linking domains
Popularity index

The 0–100 score comes from three things: the place in the popularity index, how central the domain sits in the link network, and the strength of the sites that link to it. The raw total goes through a scaling curve and becomes the final score. Sort referring domains by strength, see the risky ones flagged, export CSV. Compare several sites side by side.

4 · Link gap

Find the sites that link to your competitors but not to you.

Site (sample)StrengthCompetitor ACompetitor BYouNotice
example-guide.net64YesYesNoGuest post page
examplenews.com58YesNoNoLow risk
digitalexample.com47YesYesNoAd page

Enter your own domain and your competitors. Get the sites that link to competitors but not to you, sorted by strength and spam risk. Sites that publish advertising or guest post pages are flagged separately; your outreach list is ready.

5 · Placement check and publisher report

Is the link still there? What kind of site did you get a post on?

example-guide.net/guest-post-12Link on the page, dofollow, page open to crawlingIn place
examplenews.com/column-postPage changed 3 days agoLink lost
digitalexample.com/blog/exampleLink on the page, nofollowNofollow

Check whether the link you placed is still on the page, whether the page is open to search engines and whether the link is dofollow. Get notified if the link disappears. Before getting a post, open the publisher report too: spam history, authority, technical state and ad page hints on one page.

6 · API

Call it from your scripts and spreadsheets.

Create a key in the panel and call the domain score, referring domains, bulk query, comparison and spam audit endpoints from your own tools. The OpenAPI definition is open without a key.

Access with a keyOpenAPI definition
API documentation

How it works

Three steps, helmet included.

  1. Type the domain.

    One by one or as a list. A bulk query takes up to 5,000 domains for scores and up to 50 domains for a quick spam scan.

  2. Kosto digs.

    It looks at the link index, the web archive, the crawl index and the live site.

  3. Read the finding.

    Score, timeline, sample pages. The decision is yours.

Who it is for

For people who work with domains and links.

SEO freelancer

Scans a site in two minutes before recommending a link to a client. Gets the finding in a form they can explain to the client.

Spam historyAuthority scorePublisher report

Limits

Know what Kosto does not do.

  • It does not guarantee rankings. No tool's score is a promise of rankings, and neither is Kosto's.
  • Traffic figures are estimates. It is not analytics data; for real visit counts, look at the site's own analytics.
  • It does not ask "is this address in the index". The spam audit only shows addresses it saw in the archive and the crawl.
  • Page-level backlinks come from a sampled crawl. It is not a complete list.
  • Search data is paid and has a quota. A cached result is free, a new one is deducted from the quota.

When you see "no signal found", it means "we do not know", not "there is none". We cannot see content shown only to search engine bots or text loaded later by JavaScript.

Kosto, in a miner's helmet, with a calm expression
I did not come across the traces I was looking for. That does not prove their absence.
Coming soonExpired domain finderWatchlistEmail alertsWeekly summaryNot available yet; we are not giving a date.

Give me the domain. I will dig through its history.

5 lookups and 1 spam audit a day are free. No card needed. For paid plans see the prices.

Frequently asked questions

What you may be wondering.

No. The Kosto score is calculated from our own link index and popularity index; other tools' scores come from different data and a different formula. Comparing two scores one to one is misleading. If you want to align the scale with values you already know, there is a calibration tool.

The link index is refreshed at regular intervals. The spam audit reads the archive and the live site at query time; the result is cached for 24 hours and you can skip the cache with "refresh". Every report shows the audit date.

No, it means "no trace where I looked". For a domain with no record in the archive we say "not enough data", never clean.

Gambling, adult content, pharma, counterfeit goods, loan and crypto scams, essay-writing services, foreign-language spam after a hack, pirated streams, hacklinks and malware. The list may change.

You pick a plan, Kosto gives you an address and an amount, you send USDT, and the plan opens once the network confirms it. The steps are in the pricing page's "how to pay with crypto" section. There is no automatic renewal.

You can ask for a refund within a short period after the first payment, if you have not used the service beyond a certain threshold. Refunds are paid in USDT with the network fee deducted.

Yes. You create a key in the panel and can make up to 120 requests a minute. There are endpoints for domain score, referring domains, bulk queries, comparison and spam audit. The OpenAPI definition is open without a key. Address: /api/v1. API documentation.

The free plan gets 5 lookups and 1 spam audit a day. The limits of the paid plans are on the pricing page. A bulk query takes at most 5,000 domains (score) or 50 domains (quick spam scan).

The "Search data" group in the panel: estimated traffic and keywords, keyword research, keyword gap, page-level backlinks, rank tracking. This data is paid and is deducted from the data budget of your plan. Every fetch button shows the amount; a cached result is free. Traffic figures are estimates.

No. Kosto is a measuring and screening tool. We do not promise rankings, and nobody can.

Sites with advertising, guest post or sponsored content pages or phrases. This is a hint. We do not know whether the site owner actually uses those pages.

The domains you enter are stored for your query history.

You cancel from the account page. The plan works until the end of the period you paid for, then returns to the Free plan. There is no automatic charge.