Side-by-side collage is the fastest way to put two or more photographs on the same horizontal baseline so viewers can compare them without flipping tabs or pinching zoom on a phone. Whether you are documenting a before-and-after renovation, lining up product color variants for a Shopify listing, preparing A/B creative for a stakeholder review, or dropping listing photos into one frame for a real-estate flyer, a single row keeps the story obvious: left to right, same lighting assumptions, same scale when you match heights. SynthQuery’s Side-by-Side Collage tool (catalog id COLL-003) runs entirely in your browser: you choose between two and five images, tune the gutter between panels from zero to fifty pixels, pick a border color (white, black, or a custom hex), decide how the shared row height should be derived, optionally cap total output width, preview the composite, then download PNG, JPEG, or WebP. Height matching rescales every source proportionally so their vertical extent aligns while aspect ratios stay honest—no squashed faces or stretched packaging. The gap pixels are painted with your selected border color, which doubles as the matte behind transparent regions when you export to JPEG or WebP. Nothing in this documented workflow uploads your bitmaps to SynthQuery servers; decoding and Canvas rasterization stay on your device, which matters for client work, medical progress imagery, and unreleased product shots. For broader discovery, start from the free tools hub at /free-tools or the full directory at https://synthquery.com/tools, then return here whenever you need a disciplined horizontal strip instead of a full grid or carousel.
What this tool does
SynthQuery follows the same interaction grammar as other imaging utilities in the free-tools collection: enqueue files, adjust controls while previews refresh, then export once the readout matches your channel requirements. Multi-image support stops at five sources to keep Canvas memory predictable on mid-range phones and to encourage intentional comparisons rather than entire contact sheets. The horizontal layout is fixed by design—this is not a freeform mood board—so marketing reviewers instantly understand the visual grammar. Gap control spans zero through fifty pixels in integer steps; zero can simulate a flush magazine spread, while ten to twenty-four pixels often matches social templates that expect air between assets. Border color applies both to explicit gutters and to any letterboxing introduced while matching heights, which keeps halos consistent when photos have different aspect ratios. Height matching offers three philosophies: shortest natural height avoids interpolation upscaling; tallest height aligns small thumbnails to a hero frame; custom height supports specs such as 1080 px tall hero strips. Max output width applies a proportional scale to the entire composition when the sum of scaled panel widths plus gaps would exceed your cap, which is how you stay inside a 1920 px deck or a 1200 px blog content column without manual math. Preview always renders PNG for clarity; downloads honor the format and quality you selected. Accessibility is handled with labeled sliders, selects, and buttons, plus descriptive preview alt text while images load.
Why five images is the upper bound
Beyond five columns, text and UI chrome on phones become cramped, and Canvas surfaces approach memory limits faster when sources are high megapixel. If you need a larger matrix, use this tool for pairwise comparisons or export two collages and assemble a grid in a dedicated design app.
Formats and transparency
PNG preserves lossless detail and supports transparency in sources. JPEG and WebP exports flatten transparent pixels using the same color as your gap fill so halos stay predictable. Pick a gap color that matches the page background where the image will embed.
Technical details
The engine measures each decoded image’s naturalWidth and naturalHeight, derives a target row height from your mode (minimum of heights, maximum of heights, or a user integer clamped to four thousand ninety-six pixels), and computes each panel width as the proportional width that preserves aspect ratio at that height. Total width equals the sum of panel widths plus gap times the count minus one. When a maximum width is set and exceeded, a uniform scale factor multiplies heights, widths, and gaps together so geometry stays self-similar; integer rounding is applied per panel, and a small correction may trim the last panel by a pixel or two so the raster never exceeds the cap. Rendering allocates an HTMLCanvasElement at the final width and height, fills the surface with the gap color, then for each panel fills the cell rectangle with the flattening matte and draws the image with drawImage from full source pixels into the cell bounds using high-quality smoothing. The implementation mirrors how design tools export stitched banners except it stays local to the browser tab. Anti-aliasing follows the user agent’s defaults along scaled edges; for razor-sharp pixel art, upscale integer multiples in a pixel-perfect editor first.
Canvas limits and performance
Both dimensions are clamped so neither edge exceeds four thousand ninety-six pixels, matching other SynthQuery imaging utilities. Extremely large camera rasters may still feel heavy on older phones; if the tab stutters, reduce source resolution upstream with the Image Resizer, then collage.
Use cases
Before-and-after storytelling is the classic use case: fitness coaches, dermatology educators, and home renovators place baseline and follow-up stills in one frame so Instagram or PDF readers see both states without swiping. Ecommerce teams align colorway variants—shoes, apparel dye lots, or matte versus gloss product finishes—so merchandising and legal can sign off on subtle differences in one attachment. Growth marketers preparing A/B hero shots export a single comparison strip for Slack or Notion comments instead of dangling two separate links that preview inconsistently. Real-estate agents combine exterior angles or living-room wide shots for print flyers where horizontal space is abundant and vertical stacking would waste paper. Construction and field-service supervisors stitch progress photos across weeks with identical row height so stakeholders perceive alignment even when camera distance drifted slightly. Researchers overlay instrument readouts next to specimen photos for internal lab notebooks that must stay offline. Educators teaching photography compare exposure brackets side by side for classroom projectors. Agencies batch these collages during fast client rounds before investing time in layered PSD comps.
Brand and campaign governance
When AI-assisted copy sits next to your visuals, run prose through SynthQuery’s AI Detector or Humanizer where your disclosure policy requires it; this collage utility only handles pixels, not text governance.
Pairing with resizing and crops
If sources mix 4:3 and 16:9 aspect ratios heavily, consider normalizing in the Image Resizer or a dedicated crop tool first, then return here for the final strip so panel widths feel balanced.
How SynthQuery compares
Desktop suites like Photoshop and Affinity offer non-destructive artboards with unlimited layers, but they require installs, licenses, and export discipline. Collage-focused mobile apps often upload masters to process in the cloud, which is a non-starter for confidential assets. Generic office tools can place images in documents, yet they rarely expose precise pixel gaps, explicit height matching, and deterministic raster export in one lightweight screen. SynthQuery targets a narrow job—two to five photos in a single row with honest scaling, visible gutters, and immediate download—without accounts for the documented client-side workflow.
Aspect
SynthQuery
Typical alternatives
Privacy posture
Documented path keeps decode and Canvas work in-browser; no SynthQuery server upload for the described collage flow.
Many web collagers and mobile editors sync through vendor clouds unless you audit their terms carefully.
Layout specificity
Fixed horizontal strip with explicit gap color and height matching modes tuned for comparison photography.
General design tools are more flexible but slower for a single-row export; slide decks add template friction.
How to use this tool effectively
Start by collecting the two to five files you are allowed to merge—JPG, PNG, WebP, BMP, or TIFF—and confirm you have rights to combine and redistribute them. Open this page, then use Browse images or drag files onto the dashed drop zone; the queue accepts up to five items and enforces a forty megabyte limit per file so mobile browsers stay responsive. Each row shows a thumbnail, filename, and controls to move the slot earlier or later in the strip because order is left-to-right in the final collage. Wait until every row finishes decoding; errors surface inline if a TIFF is truncated or a download was incomplete. Set Gap between images with the slider: zero yields a tight seam, while larger values create breathing room that reads like mat board in a gallery frame. Choose Gap / border color next—white for print handoffs, black for cinematic comparisons, or Custom with a color picker when you need a brand hex. Under Match row height, pick Shortest image to avoid upscaling noise, Tallest image when you want smaller sources enlarged to the biggest natural height, or Custom height when you already know the pixel height your CMS or ad network expects. If the combined width would exceed a delivery limit, set Max output width so the entire row—including gaps—scales down uniformly. Open Download format to select PNG (lossless, larger files), JPEG (smaller, lossy), or WebP (often efficient for web); adjust Quality for lossy formats. Watch the live preview regenerate as you change controls, verify dimensions in the readout beneath the preview, then click Download collage to save a single raster you can attach, upload, or place in a deck. If something looks soft, revisit height mode: unnecessary upscaling is the most common cause of blur.
Ordering and renaming before export
The tool does not rename files for you; downloads use a predictable side-by-side-collage suffix with the extension you chose. If your DAM requires sequential codes, rename sources on disk before uploading or rename after download in Finder, Explorer, or your DAM batch tool.
When to cap width
Email clients, legacy CMS fields, and some ad builders reject extremely wide masters. Cap width early so you are not manually scaling in another app afterward. Because scaling is uniform, aspect relationships between panels stay stable.
Stack two to five images vertically with matched width and adjustable gaps—use it when the story reads top-down instead of left-to-right, then return here for horizontal comparisons.
The tilt-shift tool emphasizes horizontal bands with selective focus—useful for wide compositions and miniature-style hero art after you line up subjects here.
Instagram’s 4:5 portrait crop utility prepares feed-ready frames; combine it with this collage when you need both strict vertical crops and side-by-side storytelling.
Brightness adjustment is a lightweight first stop before collaging when exposures differ; chain additional color tools from the free-tools index if you need contrast or saturation passes.
Frequently asked questions
You can add between two and five images. The interface blocks additional files so previews stay fast and Canvas memory stays predictable on phones. If you need more than five panels, export two separate collages or switch to a full design suite for large matrices.
Shortest sets the row height to the smallest natural height among your images, scaling taller images down so nothing is upscaled—great for crisp comparisons. Tallest uses the largest natural height, scaling smaller images up, which can soften fine detail if the sources were tiny thumbnails. Custom lets you type an exact pixel height (up to 4096) when a CMS, ad spec, or slide template dictates the vertical size.
PNG is lossless but larger. JPEG and WebP apply lossy compression controlled by the Quality slider; lower values save bytes but introduce artifacts along edges and gradients. Upscaling through tallest-height or custom heights can also look softer because new pixels are interpolated. When possible, start from high-resolution masters and prefer shortest-height mode if you want to avoid upscaling.
After computing each panel width at the chosen row height and adding gaps, the tool checks the total width. If it exceeds your cap, everything scales down uniformly—including gaps—so the final file fits inside the limit. This is helpful for email attachments, blog content areas, and projector decks that cannot accept extremely wide bitmaps.
Yes. Transparent areas are preserved in PNG exports. If you choose JPEG or WebP, transparent pixels are flattened against the same color as your gap/border setting so halos match the gutters between photos.
JPG, PNG, WebP, BMP, and TIFF are supported up to forty megabytes each. Corrupt or unsupported TIFF variants may fail decode with an inline error; re-export from your editing software or convert with another SynthQuery converter, then try again.
For the documented client-side workflow, decoding and Canvas rendering occur in your browser tab and downloads are generated locally. Standard web analytics may still record page views as on any site—review the privacy policy if you need corporate compliance detail—but your image bytes are not uploaded for this collage path.
Yes. Each queue row includes move-left and move-right controls that swap slots so you can adjust the left-to-right narrative without re-uploading files.
Fifty pixels keeps the control range meaningful for screen and print comps while preventing accidental huge gutters that would dominate the frame on mobile. If you need enormous spacing, export with a modest gap and add whitespace in a presentation template where vector guides are easier to tweak.
This tool outputs a single wide image, not multiple swipeable slides. Use it when one composite attachment tells the story. If the network expects separate files per slide, split the narrative manually or use network-native carousel upload flows after exporting individual crops from the Image Resizer or Instagram crop utilities.
Add two to five photos, set the gap and border color, choose how row height is matched (shortest, tallest, or a custom pixel height), optionally cap total width, then preview and download PNG, JPEG, or WebP.
0/5 images · JPG, PNG, WebP, BMP, TIFF · max 40 MB each
12px
When the row would exceed this width, everything scales down proportionally (including gap).
JPEG and WebP flatten transparent areas using the same color as your gap fill.
Preview
Live preview uses PNG. Final file follows your format and quality settings.