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What Is a Job Aggregator?

By The Job Alert Team · September 21, 2026

Most people searching for work use a job aggregator every day without knowing the word. It explains a lot of otherwise confusing behaviour: why one advert appears on six different sites, why a role you click is already closed, and why the site you searched cannot answer a single question about the job.

A job aggregator collects job adverts that were published somewhere else and makes them searchable in one place. It does not create the adverts. It does not employ anyone. It is an index — the same relationship a search engine has to the web.

A job board, by contrast, is where an advert is originally posted. An employer pays the board, writes the listing, and receives applications through it. The board holds the relationship with the employer. The aggregator holds a copy of the text.

How the collecting actually happens

Three mechanisms do nearly all the work.

Feeds. A board or an employer publishes a machine-readable file of its current openings — usually XML or JSON — and refreshes it on a schedule. The aggregator downloads it. This is the cleanest path: the data is structured, the fields are consistent, and removals show up when the role disappears from the file.

Crawling. Where there is no feed, the aggregator’s crawler visits pages, follows links and extracts fields from the HTML. This is messier. Job titles arrive with department codes attached, locations arrive as free text, and closed roles linger until the crawler returns.

Structured markup. Many employers now embed a JobPosting block in the page itself, in a standard vocabulary that search engines read. That markup is what allows job results to appear directly in general search, and aggregators consume it too.

Whichever mechanism is used, the result is the same shape: a stored copy of somebody else’s advert, with a link back to the original.

Then it has to be de-duplicated

The same vacancy is frequently posted by the employer, by two staffing agencies working the same requisition, and by three boards that syndicate each other’s inventory. An aggregator receives all six and has to decide whether they are one job or six.

Matching is done on title, employer name, location and description similarity — and it is genuinely hard. Employer names vary (Acme Ltd, ACME, Acme Group Holdings). Agencies deliberately strip the employer name to protect the placement fee. Locations are recorded as a city, a district, a region or a postcode by different sources.

This is why you see the same role several times. It is not padding. It is the honest output of an imperfect matching problem, and every aggregator has the same problem.

The aggregator is not the employer

This matters most at the moment you apply.

What you might assume	What is actually true
The site posted this job	An employer or a board did; the site holds a copy
The site can tell you if it is still open	Only the original source knows that
Applying here reaches the employer	You are sent to the original posting to apply there
The site checked the company	An index does not inspect what it indexes
The salary shown is authoritative	It is whatever the original text said, if it said anything

An aggregator has no contract with the employer, no contact at the company and no visibility into the hiring process. When you click through, you leave the index and arrive at the employer’s own careers site, an applicant tracking system, or the board where the advert began. That destination is who receives your application, holds your data and decides what happens next — so it is the destination’s privacy policy that governs your details, not the aggregator’s.

What aggregation means for freshness

Three delays stack up, and they are the reason closed roles persist:

1. Collection lag. A feed refreshes on a schedule; a crawler returns on a rotation. Newly posted roles appear after that cycle, not the instant they go live.
2. Removal lag. Removal depends on the source signalling it. If a role simply stops being linked rather than being explicitly withdrawn, it can sit in the index for a while.
3. Filled but still advertised. Employers routinely leave adverts up after choosing a candidate — to keep a pipeline, because the requisition is still formally open, or because nobody remembered to close it. No index can detect that from outside.

The practical habit that follows: before investing effort in an application, open the original posting and look for it on the employer’s own careers page. If it is not there, treat the copy as stale. How long do job postings stay up goes through the checks in detail.

Where Job Alert sits in this picture

Job Alert is an aggregator-backed search app. It queries a third-party service that indexes employer career sites and job boards, and it presents those results to you in 62 countries.

To be explicit about what that means:

• Appers Systems does not post, own, endorse or independently check any listing in the app. The listings belong to whoever published them.
• The app opens the employer’s original posting in your browser. It does not submit an application for you, and it cannot track one.
• A role can be filled or withdrawn before the upstream index drops it, so a listing appearing in the app is not proof the role is still open.
• We do not name the upstream provider, because the app’s connection to it is deliberately hardened in the client. What matters for your decisions is the mechanism, and the mechanism is exactly the one described above.

The free tier is three searches a day and five saved jobs, with the remote-only filter reserved for premium. Saved jobs live on your device, not on a server.

Reading any aggregator well

• Treat the aggregator as a discovery tool and the employer’s own site as the source of truth.
• Click through before you write anything. The full requirements, the salary band and the closing date are often only on the original.
• When an advert has no employer name, it is an agency listing. That is not sinister, but you are applying to the agency.
• Search the same role twice, in two vocabularies. Indexes match text, so driver and chauffeur, or developer and engineer, return different sets.
• Never pay a fee to be considered for a job you found through any index.

More on the plumbing behind the app is in how it works and where listings come from.

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