SearchMEP: political affiliations and roles of Members of the European Parliament since 1979

SearchMEP is a static web application and dataset for exploring political affiliations and roles of Members of the European Parliament elected since 1979. Version 1.3 is generated primarily from the official English pages of the European Parliament and contains 54,288 fine-grained stored service-detail rows for 4,600 unique MEP IDs, covering parliamentary terms 1 to 10 and 28 countries. The web interface reconstructs these stored rows into 11,592 core political affiliation intervals for display and extraction. Stored rows represent dated fine-grained affiliation and service-detail intervals. A new stored row is created when a tracked affiliation or role changes: parliamentary term, national party, European political group, political group role, EP role, EP bodies, committee membership, committee substitute membership, delegation membership, delegation substitute membership or other service affiliations. In the application interface, displayed intervals are generated only by changes in parliamentary term, national party, European political group or political group role. Any positive source-documented gap in EP service also starts a new interval. EP roles, EP bodies, committees, delegations and other service affiliations remain searchable and exportable, but changes in these fields do not create additional displayed rows. National party labels and political group labels are preserved from the official English source pages except for one documented release normalization: `Non-attached` (T1–T5) and `Non-attached Members` (T6–T10) are represented as `Non-attached members`; untouched source snapshots retain both official variants. National parties are not harmonised. The dataset does not infer missing dates. Gender is added as a supplementary field using a conservative proxy from the official French European Parliament pages when gendered role labels such as “suppléant” and “suppléante” allow safe inference. The 565 cases unresolved by the automated proxy were reviewed manually using the official EP profile, the MEP’s first name and the EP profile photo together. After this manual review, the dataset contains 3,245 MEPs coded M, 1,355 coded F and 0 coded unknown. This release includes the responsive static application, the generated JSON dataset and deterministic gzip representation, CSV exports, View/Excel/CSV browser extraction formats, gender-inference trace data, the completed manual gender-review table, service-affiliation extraction files, documented editorial decisions, reconstruction scripts, immutable V2 JSON input snapshots and methodological documentation. The source data cut-off is 2026-07-07; manual gender review was applied on 2026-07-09; version 1.3 was released on 2026-07-23 after final integrity and interface checks. The application supports shareable filter URLs without transmitting data to an application server. Complete values chosen from filter suggestion lists match exact source labels, while freely entered fragments retain case-insensitive partial matching. `Chair or Co-Chair` is an explicit combined search option and is not a new stored role value. Second-group and second-party filters require every selected value to occur within the same temporal, term, role and service-filter scope. Search dates are limited to 1979-07-17 through the data cut-off, and an open end means ongoing at that cut-off. Displayed names are not split or inverted; documented source-aligned updates may follow the current official directory. The active release therefore uses `Zala ČERNILEC TOMAŠIČ` for MEP `256814`, replacing the earlier release value `Zala TOMAŠIČ` while retaining historical snapshots. Name sorting follows the family-name order of MEP IDs captured from the official English all-terms directory, with complete coverage of the 4,600 SearchMEP IDs, and this order is used by default in the interface. The final quality report passes JSON/CSV, ID, duplicate-row, date-order and within-MEP consistency checks. Two impossible date ranges are preserved from the raw official service-affiliation source and documented separately; neither occurs in the public political-interval table. SearchMEP is not an official European Parliament product.