| Ref | Collection | Online Catalogue Status |
| | | |
| AH | Anglesey Hunt Records and Artefacts | Available online |
| AHC | Anglesey Hunting Club Records | Available online |
| AM | Amlwch Mss | Available online |
| AO | Alun Owen Papers | Available online |
| ASH | Ashby (Ty Calch) Mss | Available online |
| BALAB | Bala-Bangor Mss | Available online |
| BA | Beaumaris and Anglesey Records | Available online |
| BEL | Belmont Mss | Available online |
| BHILL | Baron Hill Mss | Partly available online |
| BMSS | Bangor Mss | Available online |
| BOD | Bodorgan Mss | Partly available online |
| BODR | Bodrhyddan Mss | Paper catalogue only |
| BRO | Broom Hall Mss | Available online |
| BRYN | Brynaerau Mss | Available online |
| CA | Caerau Mss | Available online |
| CAS | Castell Mss | Available online |
| CEFND | Cefndu Mss | Available online |
| CEFN | Cefn Llan Mss | Available online |
| COET | Coetmor Mss | Available online |
| CORF | Corfanydd Mss | Paper catalogue only |
| CV | Carter Vincent Mss | Partly available online |
| CRV | Crawley-Vincent Mss | Available online |
| CYM | Cymru 2000 | Available online |
| CYN | Cynhaiarn Mss | Available online |
| CYNAN | Papurau Cynan | Available online |
| DarbAdd | Darbishire Papers Additional | Available online |
| DGJ | Archif Dafydd Glyn Jones | Available online |
| DIN | Dinam Hall Mss | Available online |
| ED | Edern Mss | Available online |
| GAB | Gabriel Hughes Mss | Available online |
| GAI | Gaianydd Mss | Available online |
| GARTH | Garthewin Mss | Paper catalogue only |
| GARTHA | Garthewin Additional Mss | Available online |
| GASQ | Gasquoine Mss | Available online |
| GL | Papurau Gweneth Lilly | Available online |
| GOP | Goppa Diaries | Available online |
| GWAL | Gwalchmai Mss | Available online |
| GWR | Gwredog Mss | Available online |
| GWYN | Gwyneddon Mss | Paper catalogue only |
| HENA | Henblas A Mss | Available online |
| HENB | Henblas B Mss | Available online |
| HEN | Henllys Mss | Partly available online |
| HUGH | Dr Hugh Jones Papers | Available online |
| IW | Papurau Ifor Williams | Available online |
| JMJ | Papurau John Morris-Jones | Available online |
| JOR | J.O. Roberts Papers | Available online |
| KIN | Kinmel Mss | Available online |
| LLA | Lluniau Amrywiol / Misc. Photos | Available online |
| LLE | Llwydiarth Esgob Mss | Available online |
| LLECH | Llecheiddior Mss | Paper catalogue only |
| LLIG | Lligwy Mss | Partly available online |
| LLM | Lluniau Mawr / Large photos | Available online |
| LLOYD | J.E. Lloyd Mss | Available online |
| LLYS | Llysdulas Mss | Available online |
| MAEN | Maenan Mss | Available online |
| MEUD | Meudwy Môn Mss | Available online |
| MN | Maesyneuadd Mss | Available online |
| MOR | Morfa Mss | Paper catalogue only |
| MON | Mona Mine Records | Paper catalogue only |
| MOST | Mostyn Mss | Partly available online |
| NAN | Nannau Mss | Paper catalogue only |
| NANT | Nantlle Mss | Available online |
| NEW | Newell Mss | Available online |
| NIC | Nicander Mss | Available online |
| NOR | Normal Records | Partly available online |
| NWC | Nanney Williams Collection | Available online |
| PAG | Paget Papers | Available online |
| PAMP | Pamplin Papers | Available online |
| PARC | Parciau Papers | Available online |
| PEN | Penrhos Mss | Partly available online |
| PENRH | Penrhyn Castle | Available online |
| PENRA | Penrhyn Castle Additional Mss | Available online |
| PFA | Penrhyn Castle Further Additional | Available online |
| PBRA | Penrhyn BRA | Available online |
| PQS | Penrhyn Quarry Strike | Available online |
| PBIS | Penrhyn Correspondence | Available online |
| PC | Plas Carreg Mss | Available online |
| PCO | Plas Coch MSS | Partly available online |
| PG | Plas Gwyn Mss | Available online |
| PM | Pentre Mawr Mss | Available online |
| PN | Plas Newydd Mss | Available online |
| PYA | Porth yr Aur | Partly available online |
| PYAA | Porth yr Aur Additional | Partly available online |
| PRES | Presaddfed Mss | Paper catalogue only |
| RDG | R.D. Griffith Papers | Paper catalogue only |
| RHIW | Rhiwbach Mss | Available online |
| RST | R.S.Thomas and Elsi Eldridge Papers | Available online |
| RTJ | Papurau R. Tudur Jones | Available online |
| RTP | R.T.Pritchard Papers | Available online |
| SC | Sale Catalogues | Available online |
| SEAR | Searell Papers | Available online |
| SHANK | Shankland Mss | Available online |
| STAP | Stapleton-Cotton Mss | Available online |
| STM | St Mary’s Records | Available online |
| TR | Papurau Tomos Roberts | Available online |
| TRE | Tregayan and Aberdunant Mss | Available online |
| TRALL | Trallwyn Mss | Available online |
| TYN | Tynygongl Mss | Available online |
| UCNW | Casgliad y Coleg / UCNW | Partly available online |
| WCE | William Charles Evans Papers | Available online |
| WHEL | Wheldon Papers | Available online |
| WYNN | Wynn Hall Mss | Available online |
| WHC | Whitney and Clifford Mss | Available online |
| YALE | Yale Mss | Available online |
