SpinSpotter, a new start-up, could send shivers across many a newsroom. The Web tool, which went live Monday at the DEMO technology conference in San Diego, scans news stories for signs of spin.

Users download Spinoculars, a toolbar that sits atop the browser and lets readers know if the story they are reading has any phrases or words that indicate bias. (It works only in Firefox now and will work in Internet Explorer in a couple weeks.) It highlights those phrases in a big red box, and readers can click to find out what exactly SpinSpotter found wrong with the phrase.

SpinSpotter founder and chief creative officer, Todd Herman, put it a different way: “Our mission is to make news media transparent.”

The Spinoculars find spin in three ways, said Mr. Herman. First, it uses an algorithm to seek out phrases that violate six transgressions that the company’s journalism advisory board came up with based on the Society of Professional Journalists’ Code of Ethics. They are personal voice, passive voice, a biased source, disregarded context, selective disclosure and lack of balance. Soon SpinSpotter will add a feature that will alert readers if a story uses suspiciously similar language to a press release.

SpinSpotter’s algorithm also uses a database of common phrases that are used when spinning a story. Finally, readers can flag instances of spin. Other SpinSpotter users can see these flags, and the reported phrases will enter the spin database. Contributors are given trust ratings that are determined by the algorithm along with a group of journalism graduate school students.

Monday Mr. Herman flagged a story on CNNMoney.com. His first problem was the headline: “How plan protects taxpayers.” It assumed that the plan would protect taxpayers, a misuse of the reporter’s voice, he thought. The story cited a “bond guru,” which Mr. Herman thought also misused the reporter’s voice by failing to provide evidence that the source was indeed a guru. It also quoted a university lecturer without stating his affiliation with a Web site, which Mr. Herman thought was selective disclosure.

I decided to try out SpinSpotter, with the trepidation only a journalist would feel. Searching for spin is one of the country’s favorite pastimes, especially this political season, and The New York Times fields a fair amount of that criticism. Would big red boxes cover the Web site?

First, I clicked on a bunch of my recent stories. All clear. No spin. I adjusted the spin level down to 1 (5 grants the highest tolerance for spin, 1 the lowest.) Still no spin. Relieved, I searched some other stories on NYTimes.com. No spin. I tried another news site. Still no spin.

Desperately wanting to find spin, I went to the Silicon Valley gossip site, Valleywag, which makes no qualms about writing stories with its own snarky spin. Yet calling PR people “the most annoying people in our inbox” did not raise any red flags on SpinSpotter. Writing that Rupert Murdoch is “not going to have any luck recruiting an outsider to fill the spot” of MySpace China chief executive wasn’t spin either.

That is partly because SpinSpotter has started out with very few phrases in its database of spin, said Mr. Herman. “Referring to something as spin is a pretty serious thing,” he said. “We don’t want to go through vandalizing properties. We would like to do this responsibly.” The company will watch how users react to the red flags that its algorithm catches and and decide how vigilant to be, and as users report their own spin sightings, the spin database will gradually fill up with user entries. SpinSpotter acknowledges at the top of its Web site that it is “very beta.”

Still, there are limits to an algorithm. It can spot phrases, but cannot account for context or tone.

After more searching, I finally found a news story on NYTimes.com in which the Spinoculars discovered spin. Right there in the lede of a story in the Washington section was a big red box highlighting the words “politically difficult” in this sentence:

Congressional Democrats have scrapped plans for another vote on expansion of the Children’s Health Insurance Program, thus sparing Republicans from a politically difficult vote just weeks before elections this fall.

I clicked on the little S that showed up next to the red box to get SpinSpotter’s verdict: the phrase “politically difficult” revealed too much of the reporter’s voice. “Politically difficult in whose mind? By what standard?” SpinSpotter asked.

To be sure, the writer did not cite who exactly thinks the vote might be politically difficult. Was it spin, or was the writer helpfully drawing upon his knowledge of current tensions between Congressional Democrats and Republicans and the sensitivity of a particular bill to give readers a fuller picture?