MDPI Journals in 2026: A Quality Assessment by Signal, Not Stereotype

At the publisher level, MDPI has several legitimacy markers that are hard to dismiss.

MDPI's own public materials state that:

• hundreds of its journals are indexed in DOAJ
• more than 300 MDPI journals are indexed in Web of Science
• many titles are also indexed in Scopus
• the publisher follows COPE principles in its research and publication ethics framework

Those are not trivial signals. A fake or obviously predatory publisher does not usually maintain that scale of formal indexing presence.

MDPI's ethics page also states that editorial boards are independent, that manuscripts undergo ethics checks, and that the publisher follows COPE guidance on authorship, conflicts, misconduct, and peer-review integrity.

That means the serious critique of MDPI is usually not "this is a scam publisher." It is more often:

• can quality control stay reliable at this scale?
• do some titles move too fast?
• are special issues being used too aggressively?
• does the field I care about trust this journal?

Those are different questions, and they matter more.

The real assessment happens at the journal level.

For example, the current repo dataset tracks MDPI-linked titles such as:

• Molecules
• Sensors
• Nutrients
• Applied Sciences
• Remote Sensing
• Materials

These titles do not all sit in the same reputational position.

Molecules

The journal page says Molecules is peer reviewed, open access, indexed in Scopus, SCIE, PubMed, MEDLINE, PMC, and other major databases. It also reports a 2024 impact factor of 4.6, a first decision around 15.1 days, and acceptance to publication in 2.6 days for papers published in the second half of 2025.

That combination creates both appeal and suspicion.

Appeal because:

• it is clearly visible and indexed
• chemistry authors know the journal exists
• the workflow is fast

Suspicion because:

• the timeline is so fast that some researchers immediately question review depth
• the volume and speed fit the classic "scale first" critique of MDPI

Both reactions are understandable.

If there is one metric that drives MDPI reputation, it is speed.

Fast review is not automatically bad. Many researchers are tired of journals taking four months to assign an editor and nine months to send a trivial rejection.

But very fast review becomes a credibility problem when authors infer that:

• reviewers did not have enough time
• editor oversight was thin
• the journal may be privileging throughput over filtration

MDPI journals often publish timing data proudly. That is transparent, but it also forces authors to ask whether the speed reflects operational efficiency or a lighter editorial bar.

The answer varies by title.

That is why you should not treat "fast" as either a positive or a negative by itself. Fast plus respected board plus solid published papers can be fine. Fast plus weak field reputation plus thin article quality is a red flag.

The fairest serious criticism of MDPI in 2026 is unevenness.

A lot of researchers do not believe every MDPI journal is bad. They believe the portfolio is too variable to trust automatically.

That view is reinforced by:

• the huge number of journals and special issues
• inconsistent editorial experiences reported across fields
• periodic reevaluation or scrutiny of particular titles by indexing services
• the sense that a journal's strength may depend heavily on its editor-in-chief and board, not just the publisher

Retraction Watch's reporting on reevaluations and downgrades has amplified this perception. Even when a concern applies to a subset of journals rather than the whole publisher, it contributes to the broader sense that authors need to inspect titles carefully instead of assuming publisher-level safety.

That broader sense is reasonable.

If you are considering an MDPI journal, do not ask "Is MDPI okay?" Ask these:

This framework is not anti-MDPI. It is just how careful researchers should evaluate any large publisher portfolio that varies widely across titles.

An MDPI journal can be a reasonable choice when:

• the specific title is indexed where your field expects it to be indexed
• your audience actually reads it
• the published papers look comparable to other mid-tier journals in the space
• the APC is manageable or covered
• you value speed and open access
• the manuscript is strong but not clearly aimed at a more selective society or flagship field journal

For some technical, applied, or interdisciplinary work, this is a real use case. The paper may need visibility and speed more than prestige compression.

This is where a lot of the discomfort sits.

Special issues are not inherently bad. Many good journals use them. But MDPI's scale of special-issue publishing has made some researchers worry that topic volume and guest-editor recruitment can outpace careful curation.

Once that happens, the journal's reputation stops depending only on peer review. It starts depending on whether the community believes the issue pipeline is being governed tightly enough.

That is one reason some MDPI titles can look strong on paper and still feel reputationally unstable in conversation.

The positive case is not empty marketing.

It is true that MDPI offers:

• immediate open access
• high discoverability
• fast workflows
• wide indexing across many titles
• journals that in some fields are fully mainstream

It is also true that many researchers publish solid work in MDPI journals without harming their careers.

Blanket dismissal is lazy.

The skeptical case also gets real things right.

It is reasonable to worry when:

• publisher growth is very rapid
• article volume is huge
• reported review times are extremely short
• quality appears inconsistent across titles
• external scrutiny has touched some journals in the portfolio

Blanket endorsement is also lazy.