Magic Eraser + beehiiv: Newsletter Hero Images, Boost Partner Discovery, Recommendations

No native plugin — Magic Eraser is a web/iOS/Android image editor that runs outside the beehiiv post composer. The workflow is: prep images in Magic Eraser, export at full resolution (PNG or JPEG), then upload to beehiiv through the standard image-upload flow in the post composer. beehiiv's image pipeline handles the WebP conversion, responsive srcset, and CDN distribution from there. For most writers, the lack of a direct plugin isn't a friction — image prep happens in batches at a different point in the workflow than post writing, and the separation actually helps with consistency.

beehiiv recommends 1200×675 (16:9 aspect) as the source for post thumbnails. This dimension gives the platform enough resolution for the post-page render, the responsive downsampling to recommendation-feed thumbnails, the email-delivery render, and the 1200×630 OG share card (which is close enough to 1200×675 that the platform crops cleanly to the OG aspect). Magic Eraser's AI Fill outpaint solves the common composition problem of phone-camera source photos that aren't natively 16:9 — start with whatever source you have, AI Fill out to 1200×675+ with subject roughly centered, and beehiiv's responsive pipeline handles the rest.

Both render at 1200×675 with the same technical specs, but the conversion goals are different. Regular post thumbnails sell the click on a specific post to a reader who already knows your publication. Boost partner imagery sells the subscription on your publication as a whole to a reader who doesn't know you yet but is browsing other publications' partner-recommendations. The Boost imagery has to telegraph 'what kind of publication is this' — the topic, the tone, the audience — in the 320-400px discovery-feed thumbnail display. Composition-wise: stronger brand-identity elements (publication logo or signature visual mark), subject prominence that doesn't require the viewer to already know the post context, and color grading that matches the publication's standard recipe so a subscriber clicking from Boost lands on a visually-consistent publication.

No. Upload the highest-quality source — beehiiv's image pipeline serves automatic WebP, builds responsive srcset for every breakpoint, and applies its own compression based on viewport and connection. Pre-compressing images before upload (saving as 80% JPEG, for instance) just compounds with beehiiv's own compression and produces visibly worse output at every render size. Magic Eraser exports at full quality by default — keep that quality through the upload step and let beehiiv handle downstream optimization. The exception is email-newsletter inline imagery where Gmail's 102KB clip threshold forces the file-size constraint: use JPEG quality 75-80 for image-heavy posts to fit the budget.

Yes, and this is exactly the right discipline for multi-platform newsletter publications. Save your publication's visual recipe (AI Filter color grade, Background Eraser brand palette, composition discipline, typography template if applicable) once in Magic Eraser. Apply the same recipe to images regardless of whether they're heading to beehiiv (1200×675 post thumbnail), Substack (1456×816 post hero), Ghost (variable per theme), or any other platform. The subscriber reading across multiple platforms sees the same visual identity, which is the brand-recognition discipline that compounds reader engagement across platforms.

Not directly. beehiiv's discovery surfaces are different from Substack Notes — beehiiv emphasizes Boost partner discovery, the recommendation network, and the in-product publication feed rather than a microblog format. For publications growing on beehiiv, the visual-discipline focus is the post thumbnail and the Boost partner imagery rather than a daily microblog cadence. For publications running on both platforms, the Substack Notes cadence (3-7 image-bearing Notes per week) and the beehiiv Boost partner imagery work as parallel growth surfaces with different visual brief shapes.

beehiiv's post composer handles upload, cropping, and basic positioning of images. Magic Eraser handles operations beehiiv's composer doesn't: object removal (distractions, unintended people in the frame, watermarks from stock-photo sources), background swap (cluttered home backgrounds to clean brand-color), AI Fill outpainting (extending source photos to the 1200×675 thumbnail aspect or 1200×630 OG share-card aspect), and AI Enhance (upscaling and sharpening low-light phone photos to retina-display resolution). The right shape is sequential: prep in Magic Eraser first for the major transforms, then upload to beehiiv for the final positioning and post composition.