What's new in Cella 1.0

Cella 1.0 opens PDF drawing sets the way architects and contractors use them, lets you mark them up, measure them and hand them on as ordinary PDFs that Acrobat and Bluebeam read. Cella is $149 once, with every 1.x update: one key covers one computer (Mac, Windows or Linux) and one iPad (the iPad app is coming). A 14-day free trial starts the first time you open Cella, with no sign-up. When it ends without a key, Cella becomes view-only: files still open, zoom, search, show layers and markups, and print, and marking up, measuring and saving need a key (Buy Cella… on the toolbar, or Enter License Key…). There is no account, and nothing leaves your computer unless your office syncs through its own Atrium server.

Opening, reading and printing (these stay open after the trial):

The Welcome window: Open PDF, Open Folder as Set, a place to drop files, and your recent documents and sets as cards with a picture of the first sheet and their sheet and markup counts.
During the beta, the Welcome window carries a Beta card: the beta guide, Report a Bug… and what’s new in 1.0, with a Don’t show again box.
The Welcome window also has a Try the sample set card: Open the sample drawing and Open the sample set copy the bundled clinic floor plan, and a three-sheet set made from it, into Documents/Cella Samples and open them, never over a copy you already have. The card goes once you have opened the sample.
Large sheets and 200-sheet sets open without waiting. Pan and zoom hold their place as you move between sheets. A synthetic 95 MB, ten-sheet set built like a CAD export (3,000 blocks, 400 fonts, 15,000 named views) opens in 0.75 to 0.83 seconds (it took 1.15 to 1.19) and shows its first sheet in 1.6 to 1.9 seconds (it took 2.9 to 3.7).
Damaged files are met with care: of 201 deliberately broken PDFs used in testing, 185 open and save, repaired where needed, and 16 are refused with a reason in plain words; none hangs or crashes, and 40 damaged Bluebeam tool sets and markup files import without a crash.
Scanned sheets draw about five times sooner (a 40 MB scan in 0.9 seconds, down from 5.0), and the Markups List and Properties keep up with every edit on sheets with thousands of markups.
Crowded sheets are lighter to work on. Markups are drawn on a raster layer that a sheet with 5,000 pen strokes fills in 69 to 73 ms (it took 179 to 199). Adding or deleting a markup updates the Markups List in place, in about 1 ms with 15,000 markups (31 to 36 ms before), and the first model of a large set loads in parts: on a 300-sheet set the list's first rows appear in about 0.67 seconds instead of 1.2.
Sheets run as a filmstrip under the drawing, labelled with the sheet numbers read from the title blocks and the number of markups on each. View, Sheets at Left puts them in the sidebar; the Bookmarks tab lists the PDF's outline.
Search the drawings' text and the markups, with Match Case, Whole Word and regular expressions. Select the drawing's text as in Preview and copy it.
PDF layers on and off, clickable sheet references, and links that follow.
Every markup, measurement, comment and status from Cella, Bluebeam or Acrobat, in a compact Markups List grouped by subject, sheet, author or status with counts and totals. Form fields show their values.
Markups List views: save the list's sort, grouping, filters and columns under a name and pick it again in any document. Default, Review and Take-off come built in, and views travel in profiles.
Print with the Print sheet: this sheet, all or a range, markups on or off, Fit to paper, Actual size or a custom scale, tiling for large sheets, grayscale, Print as image (each page sent as one picture at 150, 300 or 600 dpi, for printers and print shops that want a flattened image) and Print as PDF.
Split View shows two sheets of a document side by side or stacked, kept in step, or another file read-only beside this one. Links, Spaces, scales, the recognised words of scanned sheets and the firm's standards show in both panes, and a change in one appears in the other.
The command palette (Command-K) finds any command, sheet, tool or markup. Documents open in window tabs. Invert Drawing turns a sheet white-on-black for night work.
Help, Keyboard Shortcuts (Command-slash) lists every shortcut; the keyboard reaches every panel, and every control is named for VoiceOver, Narrator and Orca. On the Mac, sheets and dialogs start on their first field, answer Return and Escape, and say why a control is off. Light and dark appearance throughout.
Change any shortcut on the Mac in Settings, Shortcuts: every menu command and tool key, with a search field, a warning before a key moves from another command, and Restore Defaults. Your keys travel in a profile, and a firm profile can set them for everyone.

Marking up:

Clouds, callouts, text boxes, notes, arrows, lines, rectangles, ellipses, polygons, polylines and pen. Highlight, underline and strikeout follow the words, also from the text's context menu.
A stamp library (Approved, Reviewed, For Construction and more), stamps that fill in the date, time and your name, and Create Stamp for your own. A stamp takes a font, a size and bold or italic from the options row. Signatures you draw, type or import, placed with the date.
Your signature pictures are kept encrypted on your computer, with a key only your account can use (the login Keychain on a Mac, Windows data protection, the desktop keyring on Linux); ones saved before are encrypted the first time Cella reads them. They are never shared to a project's Project Tools, and exporting a tool set that holds them says first that the file will carry them as plain pictures.
Digital signatures: Document ▸ Sign Digitally… signs the file with a certificate from your Keychain (on Windows your certificate store; on Linux .NET's store or a .pfx file). The signature can be visible over your signature picture or in a box with your name, the date and the reason, or invisible, and can lock the document as certified. Document ▸ Signatures… lists who signed and whether each signature is still valid. Signing adds to the end of the file, so earlier signatures stay valid, and a certified document is held to its level: no change, form filling and signatures only, or markups too.
Revision clouds with numbered revision tags, the Revision Schedule and a live schedule table on the sheet.
Detect Revisions reads the revision table in every sheet's title block and fills in the Revision Schedule, marking each sheet with its latest revision for the Sheet Index, transmittals and file renaming; sheets that disagree about a revision are flagged before anything changes, and one Undo takes it back.
Sequences: text boxes or callouts that number themselves as you place them (1, 2, 3; A, B, C; D-01), with Renumber.
Replies, status, and a history of who created, changed, replied to or re-statused each markup and when. Show Changes Since outlines everything changed after a date or the last revision.
Align, distribute, match size, group, copy and paste style, rotate and flip, bring forward and send backward, and type an exact position and size.
Links you draw (to a sheet, a view, a web address or a file) and Spaces, named regions the Markups List can group by.
Create Spaces from Rooms: Cella finds the rooms the walls close on a sheet or every sheet and proposes a Space for each, named after the text inside it (OFFICE 201); tick the ones you want and they are made in one step, with the markups inside taking their names.
The floating tool palette (View, Tool Palette) holds the tools and the current tool's options beside the drawing; the document name sits centred in the title bar.
Text, callouts, stamps and legends on a rotated sheet read upright, in Cella and in other viewers.
Edit Text (Shift+T): click a line of the drawing's own text and retype it. It is rewritten in the sheet itself, in the same font, size, colour and place, as one step of Undo; A paragraph is edited as one and broken into lines again at its own width; text in a block placed once is edited too; a letter the file's font doesn't carry is written with a matching replacement font, and Cella says so; it says plainly when it can't (a block placed several times).
Everyday editing is smoother: text boxes, callouts and notes spell check as you type (Settings, Check spelling while typing), double-clicking a length's value lets you type the length and double-clicking a count renames it, Esc backs out of a field in Properties, and a text box keeps what you typed when you click another sheet.
Snapping as you draw, move and resize: to the drawing's linework, the corners and baseline of its text, the edges of placed pictures, and your other markups' ends, corners and centres, with a dashed guide when a point lines up with another markup, and to equal spacing: a markup moved or drawn beside a row of others snaps to the same gap they have, or midway between two, and the gaps show with their distance. The Snap pull-down in the status bar turns each kind on or off; hold Command to draw, move or resize free (Command-click still follows a link on a markup).

Measuring and take-off:

Set Scale or calibrate, then measure length, polylength, area, perimeter, count and volume, with dimensions, Angle and Radius tools, arc segments and typed lengths such as 12'6. Points snap to the linework, text and other markups.
Scale regions for detail sheets, a scale applied to one sheet, sheets of the same size or all, and cut-outs: an opening taken out of an area or volume.
Slope and 3D length for pipe runs and roofs: give a length or polylength a slope (1:12, 8 % or 4.5°) or a rise in Properties, and it shows its true length beside its plan length; a polylength whose legs change grade has a Segments table with a slope or rise for each leg. The Markups List, the CSV and Excel export gain 3D Length and Slope columns, and the totals add the true lengths.
Dynamic Fill (Shift-Option-F on the Mac): hover inside a room to see the region its linework encloses and its area, and click to make an Area measurement of it, with a Fill gap setting that closes door openings. A region that is not closed is refused with a note to raise Fill gap or draw the area.
Counts with a symbol, running numbers and a total.
Visual Search: drag a box around a symbol (a door swing, a receptacle, a fixture tag) and Cella finds every other one on the sheet or the whole document, turned or a little larger or smaller if you like, lists them by sheet, and places a Count on each or marks them for redaction in one step.
The Markups List as a take-off: groups with counts and subtotals, totals under the list, a CSV with the same subtotals, and a markups summary PDF.
Export to Excel: the listed markups as an Excel workbook with dates as dates, lengths, areas, volumes, counts and costs as numbers, a frozen header and a Totals row that adds up; optionally a worksheet per group. For one file or the whole set.
Take-off summary: File ▸ Export Take-off Summary… sums the measurements per subject in a column per space, layer, sheet or status (or file, for a set), with units, row and unit totals and your cost columns beside them, as an Excel workbook or a CSV; Export to Excel can add it as a second worksheet.
Export Markups to DXF: a sheet's markups, or every sheet's, as a CAD drawing in the sheet's real units from its scale, with each Cella layer or subject as a layer, colours and line weights kept, measurements with their values and each markup's id and columns along for the ride.
Custom columns that are text, number, choice, checkbox or a formula such as area * [Unit Cost], with column totals in the list, the group headers and the CSV.
Insert Legend: a live table of the sheet's markups, by subject, status, author or layer, that stays current as you draw.

Sets and new issues:

Compare Documents lines up two issues, finds what changed and clouds each change on layer Compare. Compare With overlays two issues in red and blue.
Compare Sets (File, Set) compares a whole issue with the previous one: sheets are paired by sheet number whatever the files are called, every changed sheet is clouded with its count, new and removed sheets are listed, and a Compare Report PDF shows each change.
Rename Files from Sheets (File, Set) names every PDF of a set after its sheet number and title by a pattern you choose, shows each old and new name with any clashes before anything moves, keeps markups, sync links and the set's order with the files, and Undo Rename puts the names back.
Overlay Pages draws two to four sheets over each other in blue, red, green and magenta, aligned automatically or by picked points, inserted as a new sheet or saved as a PDF.
Slip-sheet a newer issue into a file or a whole folder set with every markup in place. Link Sheet References makes every sheet number clickable.
Rotate, reorder, insert, extract and delete sheets, all undoable. Rename sheets, or Detect Sheet Numbers from the title blocks; names are saved as page labels that Acrobat and Bluebeam show. Bookmarks can be added, renamed, nested and reordered.
Sheet Index reads the drawing index off the cover sheet and names, titles and orders the set. Print Set prints a set as one job with a transmittal cover, and Export Transmittal writes the index as a PDF.
With a folder set open, the Whole Set Markups List, Whole Set search with Replace in markups, and File, Set: a summary PDF, CSV, flatten, status and columns across every file.

Documents:

Saved as standard PDF annotations with appearances, so Acrobat and Bluebeam show your markups exactly; markups other people made in Revu survive the round trip, custom columns included.
Safe saving: every save goes to a temporary file, is read back and checked, and only then replaces the original. Saves add your changes to the end of the file, so they are quick on big sets and digitally signed drawings stay signed (page operations, flattening and Headers and Footers add too); when a save would have to rewrite a signed file, Cella asks first. Serialising a save of a 300-sheet set with 15,000 markups takes 13 to 25 ms where a full rewrite took 254. After 25 appended saves of an unsigned file Cella rewrites it once and says "Compacted" (Settings ▸ Compact files); File ▸ Compact File does it on demand. Autosave every two minutes, with recovery after a crash. Encrypted PDFs that need no password open and save encrypted.
Fill PDF forms on the sheet, then clear, flatten, or export and import the values as JSON or FDF.
Apply Redactions writes a copy with the text, linework and image pixels under each mark removed, not just covered: lines and fills crossing a mark's edge are cut at the edge, letters only the marks showed are taken out of the embedded fonts, shadings are cut out, and the copy is read back and checked ("Verified: nothing remains under 7 marks"). Mark every hit of a search at once (bookmarks naming it go too), and remove embedded files and metadata in the same step.
Reduce File Size makes scanned sets small enough to send: choose Good for sharing (150 dpi), Small for email (100 dpi) or your own resolution and quality, and scans and photos are resampled and stored as JPEG, gray scans staying gray; black-and-white scans are stored as fax-style CCITT Group 4, at 200 dpi or finer so line work stays legible (a 600 dpi plan scan comes down to about a tenth); the summary shows what the pictures and scans weighed before and after. Drawings and pictures with transparency are left exactly as they were.
Combine Files with a bookmark per file, Reduce File Size with a before-and-after preview, and Headers and Footers with page numbers, dates, sheet labels and Bates numbers.
Recognize Text (OCR) makes scanned sheets searchable and selectable: the words are read on your computer, kept beside the file, and used by search, Whole Set, copying, highlighting, redaction marks and Detect Sheet Numbers; optionally written into the PDF as invisible text for other apps. A setting reads scanned title blocks for their sheet numbers automatically. On Windows it uses Windows' own text recognition; on Linux it uses Tesseract if you have installed it (not bundled).
View ▸ Show Recognized Text shows every recognized word's box on a scanned sheet, with uncertain words in amber; a double-click corrects a word or removes it (undoable), search uses the correction at once, and a later Recognize Text keeps your corrections.
Split Document by sheet ranges, every few sheets, top-level bookmarks or discipline letters (A-, S-, M-), with the files listed before they are written. Insert blank pages in Arch, ANSI or ISO sizes; crop pages by margins, a size or a box drawn on the sheet; resize pages onto another paper with the drawing, markups and scale following. Export sheets as PNG or JPEG pictures at up to 600 dpi, and put a stamp on every sheet in one step.
Insert Image Pages turns photos and scans (JPEG, PNG, HEIC, TIFF) into sheets, one per picture, named after the files: at the size the picture's resolution gives, or fitted to this sheet's size or a paper. JPEGs go in without recompression. On the Mac you can also drop pictures on the Sheets filmstrip, and on a synced document the new sheets reach the whole project.
Export Flattened Copy for the contractor's issue while your working file stays editable.
Export PDF/A-2b Copy for record sets: markups flattened, fonts embedded, an sRGB colour profile and archive metadata, with a list of what was changed or left out (links that open programs, scripts, attachments, unless you keep them as PDF/A-3) before you save. The copies of our test sets pass the veraPDF 1.30.0 PDF/A-2b validator (PDF/A-3b with attachments kept), and drawings that use CMYK colour or fonts Cella has no replacement for may need attention.
The Tool Chest, with import of Bluebeam Revu tool sets (punch keys, symbols, and picture stamps, which come in as drawn linework rather than pictures), Manage Tool Chest, and tool set export as .btx. Markups export and import as Bluebeam .bax or Cella JSON; Revu image stamps and file attachments in a .bax come in whole. Area cut-outs are read and written the way Revu is believed to keep them.
Project Tools: share tools from your Tool Chest with everyone on a synced project. They appear under Tool Chest, Project Tools for every member while a document of the project is open, offline too; anyone on the project can add or remove them (Manage Tool Chest, Project Tools, on the Mac; Windows and Linux show them). Needs the October 2026 Atrium.

Working together:

Sync through Atrium, the sync server your office runs or Sorted Solution hosts for you: every markup reaches everyone on the project, changes queue while you are offline and are kept if you quit before they send (pages inserted offline included), and Update Sheets from Project slip-sheets a newer issue someone uploaded.
Sheets sync too: turn, move, insert (from a file), delete or rename a sheet and it changes on everyone's copy, with its markups. So do the custom columns, sequences, the revision schedule and bookmarks, and a sheet's scales, scale regions, links and Spaces, which follow their sheet when it moves. Undo and Redo reach the whole project too: each person undoes their own sheet changes, and every copy follows. When two people change the same thing at once, the last change stands and the other person is told. A sheet you picked in a dialog is the one acted on even if someone moved it meanwhile; if someone deleted it, nothing changes and Cella says so.
On the Mac you see who else is on the sheet: their pointers, their selections, and their initials in the status bar.
The Atrium admin page lists, per project, its Project Tools (with Clear Project Tools), the client ids (with Release), the open connections against their limit and who is on each document, the database (size, last backup) and an audit log of token rotations, revoked devices and cleared tools. Atrium had an adversarial security review before release: six findings were fixed, each with a test that failed before, including a member's edits being hidden from another member and open connections outliving a removed member, and the few it leaves open are written down with their reasons in its SECURITY.md.
Profiles: your tool sets, stamps, columns and settings as one file for the office to import, with an optional firm profile that updates everyone at launch.
Import a Revu profile (.bpx) with File, Profiles, Import Profile…: its tool sets, its custom columns (text, number, choice list, checkmark and formula; a date column comes in as text) and its Markups List layout as a view, each with a checkbox before anything is installed, and a list of what isn't carried (toolbars, keyboard shortcuts, Studio settings, stamps). Cella reads the .bpx as Revu is believed to write it; no real Revu profile export has been checked yet, so if yours doesn't come in as it should, send it to us.
Firm standards (Mac): a profile can carry the firm's style sheet: each tool's colour, width and font, the hot colours, Subject and Status lists, default scale and measurement format, initials or full names, header and legend presets, stamps. Lock what every seat must follow (shown disabled, "Set by" the profile) and leave the rest as defaults; build them in Manage Profiles ▸ Standards.

Windows has an installer, Cella-1.0-Setup.msi: it installs for you alone without an administrator password, adds Cella to the Start menu and to a PDF's Open with list, and later updates install over it; the zip remains for anyone who prefers it.

Known limitations in 1.0:

There is no iPad app yet. Your key already allows one iPad; the app follows as a free update to Cella 1.x.
The Windows and Linux builds have not yet been run on those systems; they follow as an update for the same key. They carry the same features, but all of it is untested until that first run, and the Windows installer has not been run either (if it fails, use the zip). Visual Search has only a minimal control there, a picture dropped on the Sheets strip is not taken, and Project Tools show read-only. Windows prints the copy as pictures at up to 300 dpi, and its text recognition reads upright text only. On Linux, Recognize Text needs Tesseract installed (not bundled), and the Tool Palette and a detached Properties or Markups List open where the window manager puts them.
On a synced document, Undo of a sheet change undoes it for everyone; a step whose sheet someone else deleted is skipped with a note. An undo of an older link or Space step after someone else changed the same one puts your version back. Pages inserted while you are offline are kept on disk until they upload, up to 64 MB of them; past that, Cella says so, and those are lost if it quits before they upload. An Atrium server from before 1.0 syncs markups only (scales, scale regions, links and Spaces stay on each person's copy), and every member needs the 1.0 Cella to get sheets and columns. Seeing who else is on the sheet is on the Mac.
Crop Pages and Resize Pages sync only through an Atrium from 2026-10-15 or later (Insert Blank Page, like inserting pages from a file, syncs through any protocol-2 Atrium); with an older one a synced document refuses them until it is disconnected from Sync. A Cella from before that ignores another client's crop or resize, so its copy keeps the old sheet size.
Dynamic Fill draws curved walls as straight segments, text or hatching touching a wall can notch the outline, and the outline can bulge into a closed doorway.
Form calculations (sums, products, simple formulas), formats (currency, percent, dates, phone numbers), range checks and date pickers work for Acrobat's standard scripts; other scripts (document-level scripts, conditionals, loops, custom functions) don't run, and the status band says how many.
Edit Text writes a letter the drawing's font doesn't carry with Liberation Sans (or the matching serif or monospace face) rather than the original typeface, and says so; a paragraph it re-breaks can run down over what is below it, since nothing else on the sheet moves; it doesn't edit blocks placed more than once or nested in other blocks, Type 3 fonts or vertical text; it is refused on a document synced through Atrium and in Split View's second pane.
Recognize Text (OCR) reads handwriting, rotated and very small lettering only as well as the system's recogniser does, the first run on a Mac can take about 45 seconds while macOS prepares it, and it asks you to save first when page operations are unsaved. A scanned title block is read for sheet numbers only with the automatic setting or after a run.
Digital signatures cannot sign encrypted PDFs, add no trusted timestamp or revocation data (long-term validation), check a certificate against the computer's own trust settings (a self-signed certificate shows as not trusted), put the box at the bottom right, and count changes made after a certification that allows some without classifying them. A placed signature picture is still a picture. A document certified to allow no changes (or only form filling and signatures) takes markups only as a copy (Save a Copy…). A save that has to rewrite the file (deleting sheets leaves their objects in it until then) invalidates a signature, and Cella asks first.
Redaction keeps a letter less than about 15 per cent under a mark, a line much wider than the mark, and paths with stray operators under the paint (the summary reports what is left). Tiling-pattern cells and mesh-shading data are clipped rather than edited, a CID-keyed CFF font keeps its CIDs, and bookmarks are removed only for marks made from a search; named destinations, page labels and link targets are not searched. Check the copy before you send it.
No Revu file with a cut-out, sequences or drawing-mode counts has been checked against Cella: cut-outs are read and written in the shape Revu is believed to use, and Revu tool sets with sequence tools are imported from our best reading of the format. The .bax file Cella writes has not yet been opened in Revu itself, and attachments in a .bax stay read-only. The Excel workbook from Export to Excel and the DXF drawing from Export Markups to DXF have been read back and checked in tests but not yet opened in Excel or AutoCAD themselves. Arrowheads, fills, count symbols and stamp pictures are not carried into the DXF. Export PDF/A-2b Copy has not been run through a PDF/A validator such as veraPDF.
The Profiles window has no Escape to close, and in the Status values editor Return starts a new line. The toolbar's More menu shows an old tool key until the hidden set changes.
Sheets with thousands of fonts or pictures each (some CAD exports) are faster than they were but still heavy: the synthetic CAD-style set above took about 1.7 GB of memory to view (down from 2.2 to 2.6 GB), short of our 1.5 GB aim, and no real client CAD file has been measured. Cella still reads a whole file to open it, and a deleted sheet's objects stay in the file until it is rewritten (Reduce File Size, Export Flattened Copy).