The systematic testing of OSINT and verification tools within the RESONANT framework generated a wide range of empirical findings that shed light both on their technical performance and on their operational usability. The evaluation was conducted collaboratively by the cyberteams A (CT-A) and B (CT-B), consisting of Hellenic Police and Ukrainian Police experts, each testing the tools on distinct datasets under their respective operational conditions. While synthetic datasets were used to preserve ethical and legal safeguards, the results are representative of realistic FIMI detection scenarios and highlight the relative strengths and weaknesses of different tool categories. The comparative observations reported in this study reflect the specific testing period, tool versions, and dataset characteristics used during the controlled evaluation. OSINT tools evolve rapidly and their functionality, access conditions, and performance may change due to software updates, API modifications, or platform policy changes. Consequently, the results presented here should be interpreted as indicative of methodological applicability rather than as fixed performance rankings. Considering these remarks, in the following subsections, we provide an in-depth analysis of tool effectiveness and limitations, propose an optimised suite of instruments, and reflect on the practical challenges that arose during the testing and evaluation phases.
5.1 Tools’ effectiveness and limitations
The first category examined was fact-checking tools, which play a fundamental role in the early identification of false or recycled narratives. Across both evaluations, results showed clear disparities in performance. GPT-4o consistently outperformed all other tools, correctly identifying around 90 percent of true and 58 percent of false claims in the CT-A tests, and achieving 94 percent accuracy on true and 95 percent on false claims in the CT-B evaluation, with only minor false-positive rates. The Factual ranked second in the CT-A results, correctly classifying about 52–55 percent of true and 47 percent of false claims, though it showed higher uncertainty levels (up to 45 percent undefined). The CT-B results were broadly similar for true-claim detection, though other fact-checking repositories performed inconsistently on false claims. Traditional databases such as Snopes, Google Fact Check Explorer, PolitiFact, Truth or Fiction, AFP Fact Check, and Fake News Debunker provided only limited utility, often returning undefined outputs or failing to match phrasing with their existing entries. Collectively, the findings confirm that GPT-4o and The Factual currently represent the most reliable fact-checking instruments, while conventional repositories remain useful primarily for verifying widely circulating claims but lack the scalability and linguistic flexibility required for proactive FIMI detection.
The evaluation of website-credibility assessment tools further highlighted the uneven quality of existing resources. While the conceptual value of these tools lies in their ability to provide contextual judgments on the reliability of entire domains, their practical effectiveness was modest. NewsGuard, despite being widely cited in policy discussions, could not be tested due to its subscription-based model, and Schema.org’s ClaimReview lacked the necessary functionality for systematic evaluation. The Know News browser extension demonstrated very limited accuracy, correctly identifying credible or non-credible domains in only about 16 percent of cases. By contrast, MyWOT (Web of Trust), which was integrated after the main testing phase, proved more useful in assessing overall domain reputation. These findings illustrate a broader limitation of credibility-assessment approaches: although they can help highlight recurrent low-credibility sources, their coverage remains narrow and they often require human interpretation to validate results.
When evaluating bot detection tools, the testing process encountered major structural limitations. BotSentinel, once a widely used platform, discontinued its API service and was therefore unavailable for testing. GPTZero, designed primarily for detecting AI-generated text, was tested but could not be effectively applied to identifying automated social-media accounts. The limitation stemmed from the requirement to manually extract posts and comments from platform profiles—an action restricted under Twitter’s terms of service. These challenges highlight a broader issue in bot detection: effective analysis depends on access to authentic behavioral data, yet such access is increasingly limited by platform policies and API restrictions. Consequently, while bot detection remains an essential component of FIMI monitoring, current tools cannot be reliably deployed without sustainable and compliant data-access mechanisms.
The image and video analysis category showed strong and consistent performance, making it one of the most reliable layers of the toolkit. Reverse-image-search tools, including Google Images, TinEye, and Search by Image, achieved 100 percent accuracy, successfully identifying all instances of manipulated or recycled images within the dataset. Tools designed to detect AI-generated content produced more mixed results: ContentAtScale.ai and the Umm-maybe
model hosted on Hugging Face correctly identified about 72 percent of real images and 52–56 percent of AI-generated ones, while Illuminarty.ai performed poorly, detecting only around 20 percent of fake images and generating a high number of false positives. Image-alteration-detection tools, such as FotoForensics and 29a.ch Photo Forensics, also showed uneven but useful performance, both detected 100 percent of genuine images, while achieving 60 percent and 40 percent accuracy, respectively, on altered ones, yet their results required expert interpretation. OCR tools performed very strongly: Google Lens achieved 92 percent accuracy, ChatGPT OCR 88 percent, and OCR.space 68 percent, clearly outperforming older tools such as
NewOCR.com
(28 percent) and
OnlineOCR.net
(16 percent). Taken together, these results indicate that while multimedia forensics is not immune to errors, the current ecosystem of tools for reverse search, AI-image detection, alteration analysis, and text extraction is relatively mature and can be effectively operationalised for investigative use.
The infrastructure-level tools produced more varied results. Geo-IP detection platforms displayed a moderate degree of accuracy. MaxMind GeoIP failed to operate during testing, while IPFingerprints achieved only 36 percent accuracy in identifying the correct country. By contrast,
IPLocation.net
and Thatsthem IP Lookup reached about 70 percent accuracy, indicating that while IP geolocation cannot serve as a standalone attribution method, it provides a useful supporting layer for situating suspicious activity within broader geographic patterns. Phone-number-verification tools showed clearer contrasts:
WhoCalled.com
delivered the strongest results, correctly matching approximately 89 percent of tested numbers in both evaluations and, in several cases, even identifying partial owner information. IPQualityScore’s validator achieved about 65 percent accuracy in the CT-A results but did not return usable data in the CT-B evaluation, as it required manual entry of country codes for each query. Truecaller, despite its popularity, lacked the necessary functionality in its free version and could not be properly tested without login credentials. Overall, the results confirm that
WhoCalled.com
offers the highest reliability for phone-number analysis, while other tools remain constrained by technical or access limitations.
Finally, social-media-analysis tools proved to be the least reliable category. Many of the platforms previously used for extracting or monitoring social-media data, such as CrowdTangle, Ad Observer, and SearchIsBack, are now deprecated, restricted, or entirely non-functional. Tools designed for Twitter, including Advanced Search and Geo-Search
, often returned incomplete or false results, while Facebook-based searches and numerous Reddit utilities such as SubredditStats, Reddit User Analyser, and Apify Reddit Scraper either failed to respond or produced accuracy levels below 40 percent. Several others, including Redective, Keyworddit, and SowSearch, produced errors or unreliable outputs. Overall, the category was marked by discontinued services, false data, and API restrictions imposed by major platforms. This reflects a broader structural issue: as social networks tighten data access, third-party analytical tools rapidly become obsolete. Consequently, while social-media analysis remains essential for FIMI detection, the current landscape is unstable and requires renewed development of sustainable, API-driven, and institutionally supported solutions.
The evaluation of email-verification tools produced mixed but informative results. Among the tools tested, MailboxValidator and Thatsthem Reverse Email Lookup delivered the most consistent performance, correctly identifying around 21–22 percent of valid addresses and providing detailed analytical parameters. EmailHippo produced useful outputs but showed a higher rate of unverifiable results (18 percent) and lower overall accuracy. Emailable and
EmailValidator.com
could not be tested effectively due to account or subscription restrictions. In the CT-B tests, MailboxValidator again demonstrated stable functionality, while Thatsthem provided only partial informational outputs without explicit verification results. Overall, the findings indicate that while several email-verification tools remain limited by access or functionality constraints, MailboxValidator and Thatsthem together offer the most reliable combination for validating contact information within OSINT investigations.
Integrated and cross-domain evaluations
Beyond single-function testing, a series of integrated evaluations was conducted to measure interoperability and cross-domain performance. In the Comprehensive Media Analysis, the CT-A achieved strong, domain-specific results across all stages: 29a.ch Photo Forensics reached 100 percent accuracy in image and video analysis, Originality.ai achieved 89–90 percent accuracy in content verification, and EmailHippo succeeded in all contact-validation tests. CT-B obtained comparable but more qualitative outcomes: 29a.ch Photo Forensics effectively detected image alterations such as cloning but provided limited contextual detail; Truecaller functioned well as a mobile application for identifying spam or malicious phone numbers, and The Factual produced a “Moderately Credible” score of 51 percent for article reliability, performing effectively on most standard-length articles. Taken together, these findings demonstrate that well-configured combinations of content, media, and contact-verification tools can deliver near-complete analytical coverage, though interpretation still requires a degree of manual expertise.
The Disinformation Campaign Analysis revealed mixed levels of effectiveness across the tested tools. For CT-A, The Factual proved highly reliable, achieving 100 percent success in article analysis, while Search by Image reached 43 percent accuracy in image and video verification, and Know News scored 0 percent in social-interaction analysis. These results highlight the strong performance of text-based verification tools but also the need to integrate more robust image-analysis solutions and alternative methods for assessing online interactions. CT-B obtained generally effective outcomes, particularly for article analysis, with Know News performing well in credibility assessment and FotoForensics offering detailed image insights that nevertheless required user expertise to interpret accurately. Overall, the findings confirm that while content-verification tools are mature and reliable, image forensics and social-interaction mapping remain dependent on operator skill and would benefit from more advanced, automated capabilities.
The Cross-Platform Disinformation Analysis produced mixed results. In CT-A’s evaluation, The Factual recorded 0 percent success in article verification, while MediaBiasFactCheck achieved 100 percent accuracy in social-media analysis. CrossRef Search failed to generate relevant matches (0 percent), and MonkeyLearn Sentiment Analysis produced a 40 percent positive versus 60 percent negative sentiment balance. CT-B reported more stable outcomes, with The Factual performing effectively in assessing article reliability. Overall, the findings indicate that while textual and sentiment-analysis tools can yield valuable insights, the ability to establish reliable cross-platform correlations remains limited, highlighting the need for better-integrated analytical frameworks within the current OSINT ecosystem.
Finally, the Multi-Source Disinformation Campaign Analysis assessed the toolkit’s capacity to detect and contextualize disinformation across complex geopolitical narratives. In CT-A’s assessment, The Factual achieved 42 percent success in article analysis, Scribbr AI Detector reached 14 percent in social-media analysis, and
X.com
Explore delivered 100 percent accuracy in cross-reference detection. CT-B did not report available data for this phase. Overall, the results indicate that while content-verification tools can provide partial success in large-scale misinformation environments, automation and cross-modal integration remain limited, underscoring the continued need for human oversight and contextual reasoning in comprehensive disinformation analysis.
OSINT tools: Limitations
Although OSINT tools often seem to be very powerful while conducting digital investigations, due to the automating and fast way of functioning, still they present some significant limitations.
One major limitation is their volatility. In general, digital platforms, social networks, and online repositories constantly change their structures, restrict access, or modify interfaces, depending on various administrative, legal and other reasons. Of course, this also has an impact on an OSINT tool, as these changes may most likely prevent it from functioning. Thus, this constantly unstable situation should be taken into consideration by all interested persons/organizations, who should not rely heavily on any single automated solution.
Next, another limitation is the narrow scope of data coverage. For example, an OSINT tool may be designed to focus on a specific category, such as IP addresses, domain records, usernames, or social media accounts, while leaving many others uncovered, of high importance. This can lead to the conclusion that no single tool can ever provide a complete intelligence picture, and important information can easily be missed if investigations rely solely on tool-generated results.
Another limitation of OSINT tools is the reliability of the generated data. Many tools rely on old, outdated or limited/incomplete sources, which often results in misleading and inaccurate findings. For this reason, it is vital to properly validate and cross-check all resulting information prior to its use or dissemination.
Furthermore, a common risk that someone can fall into is the lack of security measures. This risk emerges from the fact that many OSINT tools interact directly with target platforms (domains), leaving residual evidence in the target log files. This could potentially raise an alert for the administrator, indicating that an investigation is underway. For this reason, proper operational security practices, such as anonymisation, virtual environments, and sock puppets are essential to avoid these risks.
The previous point is reinforced by the fact that there is often an “automation mentality” that gives the impression that OSINT tools are simple, requiring only pressing a button and wait for the results. This creates a false sense of security as, for sure, the tools can assist in the intelligence gathering process, but they cannot replace human creativity, analytical thinking, and reasoning.
Given the rapid evolution of OSINT platforms and access conditions, repeated testing over time would likely produce different operational outcomes.
In summary, OSINT tools are valuable for increasing speed and efficiency, but they have clear limitations. They cannot ensure complete coverage, absolute accuracy, or replace human judgment. Successful OSINT work relies on the investigator’s skills, operational security, and solid methodology, with tools acting as supporting resources rather than definitive solutions.
5.3 Practical challenges
In addition to technical performance, the evaluation process exposed several practical challenges that must be considered in the operationalisation of OSINT methodologies. The first challenge relates to sustainability: many tools tested were found to be discontinued, inaccessible, or locked behind subscription models, sometimes in the middle of the evaluation itself. This instability undermines the reproducibility of results and highlights the need for a more institutionalized approach to tool provision, potentially through public-private partnerships or open-source development.
A second challenge concerns interoperability. While the testing aligned tool outputs with structured frameworks such as DISARM and AMITT, few tools natively export results in machine-readable or standardized formats. This lack of integration increases the burden on analysts and limits the scalability of detection efforts. Without interoperability, it is difficult to link outputs across categories or feed them into broader intelligence platforms.
Third, the evaluation revealed persistent coverage gaps, particularly regarding multilingual detection and non-Western information environments. Most fact-checking repositories are heavily biased towards English-language content, while many credibility tools assess primarily Western news outlets. This creates blind spots that adversaries can exploit by targeting under-represented linguistic or regional contexts.
Significant ethical and legal constraints arise in the use of OSINT tools, particularly concerning bot detection and the scraping of data from social media platforms. These challenges are especially relevant in operational settings, where strict compliance with data protection regulations (such as the GDPR) and adherence to platform terms of service are required. While synthetic datasets can help mitigate some of these risks during development and testing, they do not eliminate the legal and ethical complexities involved in real-world applications. As emphasised in the attribution literature, technical observables identified through OSINT tools can support investigations but cannot, on their own, establish responsibility for information influence operations, which ultimately requires contextual, political, and legal assessment.31 Operational usability is another critical factor that can affect the effectiveness of OSINT tools. Even when tools are technically accurate, their practical value may be reduced by unclear user interfaces, non-transparent scoring systems, or steep learning curves. These issues can limit accessibility and hinder adoption by investigators and analysts. Beyond legal compliance, ethical considerations play a vital role in the responsible use of OSINT. Analysts must ensure that their actions are necessary, proportionate and respectful of fundamental rights. This includes avoiding techniques that could be seen as intrusive, manipulative, or misleading. In the absence of universally accepted international standards, OSINT practitioners must rely on sound professional judgment and uphold principles of transparency, accountability and integrity in their work.
Taken together, these challenges highlight the need for a robust, flexible, and ethically grounded framework for OSINT testing and validation. The RESONANT methodology provides an initial foundation by consolidating tool evaluations and aligning them with structured frameworks. However, further efforts will be required to ensure sustainability, interoperability, and accountability in the rapidly evolving ecosystem of FIMI detection tools.