Sourceful: Riverflow V2.5 Pro (free)

Riverflow V2.5 Pro is the most powerful variant of Sourceful's Riverflow 2.5 lineup, best for top-tier control and quality-sensitive outputs.

The Riverflow 2.5 series is a unified text-to-image and image-to-image family that treats generation as a production workflow, using an integrated reasoning model to plan multi-step edits and judge candidates before accepting a result. Reasoning effort is controllable via the reasoning parameter (low/medium/high/xhigh) - higher levels do more editing passes and apply a stricter internal judge, with xhigh suited to batch runs that need high repeatability. It generates at 1K, 2K, and 4K resolution and accepts up to 10 input images for editing.

Pricing is dynamic: cost is finalized per job at completion based on billable processing, so it scales with reasoning effort, resolution, and editing complexity rather than a fixed per-image rate.

Additional features (via image_config):

• Custom font rendering via font_inputs (max 2) to match brand lettering, spacing, and weight
• Custom scoring via scoring_prompt and scoring_rubric, so the reasoning model evaluates and steers each candidate against the criteria you care about
• Background control via background_mode (original, transparent, solid) and background_hex_color

See the image generation docs for details: https://openrouter.ai/docs/features/multimodal/image-generation(opens in new tab)

Note: Sourceful imposes a 4.5MB request size limit, therefore it is highly recommended to pass image URLs instead of Base64 data.